Python Parameter Passing

I'm working on making a modified version of pong for my college class and am having some trouble passing some methods. I believe I have everything set up the way it needs to to be able to do some parameter passing. The code runs fine and stops working just after the while loop in my main function. Any help is appreciated.

    import pygame

    SCR_WID, SCR_HEI = 640, 480
    class Player():
            def __init__(self):
                    self.x, self.y = 16, SCR_HEI/2
                    self.x1, self.y1 = SCR_WID-16, SCR_HEI/2
                    self.speed = 3
                    self.padWid, self.padHei = 8, 64
                    self.score = 0
                    self.scoreFont = pygame.font.Font("imagine_font.ttf", 64)

            def scoring(self):
                    scoreBlit = self.scoreFont.render(str(self.score), 1, (0,0,0))
                    screen.blit(scoreBlit, (32, 16))
                    if self.score == 10:
                            print ("player 1 wins!")
                            exit()

            def scoring1(self):
                    scoreBlit = self.scoreFont.render(str(self.score), 1, (0,0,0))
                    screen.blit(scoreBlit, (SCR_HEI+92, 16))
                    if self.score == 10:
                            print ("Player 2 wins!")
                            exit()

            def movement(self):                 
                    keys = pygame.key.get_pressed()
                    if keys[pygame.K_w]:
                            self.y -= self.speed
                    elif keys[pygame.K_s]:
                            self.y += self.speed

                    if self.y <= 0:
                            self.y = 0
                    elif self.y >= SCR_HEI-64:
                            self.y = SCR_HEI-64

                    keys1 = pygame.key.get_pressed()
                    if keys1[pygame.K_UP]:
                            self.y1 -= self.speed
                    elif keys1[pygame.K_DOWN]:
                            self.y1 += self.speed

                    if self.y1 <= 0:
                            self.y1 = 0
                    elif self.y >= SCR_HEI-64:
                            self.y1 = SCR_HEI-64

            def draw(self):
                    pygame.draw.rect(screen, (0,0,0), (self.x, self.y, self.padWid, self.padHei))
                    pygame.draw.rect(screen, (0,0,0), (self.x1, self.y1, self.padWid, self.padHei))



    class Ball():
            def __init__(self):
                    self.x, self.y = SCR_WID/2, SCR_HEI/2
                    self.x1, self.y1 = SCR_WID/2, SCR_HEI/2
                    self.speed_x = -3
                    self.speed_y = 3
                    self.size = 8

            def movement(self):
                    self.x += self.speed_x
                    self.y += self.speed_y

                    if self.y <= 0:
                            self.speed_y *= -1
                    elif self.y >= SCR_HEI-self.size:
                            self.speed_y *= -1

                    if self.x <= 0:
                            self.__init__()
                            enemy.score += 1
                    elif self.x >= SCR_WID-self.size:
                            self.__init__()
                            self.speed_x = 3
                            player.score += 1
                    for n in range(-self.size, player.padHei):
                            if self.y == player.y + n:
                                    if self.x <= player.x + player.padWid:
                                            self.speed_x *= -1
                                            break
                            n += 1
                    self.x1 += self.speed_x
                    self.y1 += self.speed_y

                    if self.y1 <= 0:
                            self.speed_y *= -1
                    elif self.y1 >= SCR_HEI-self.size:
                            self.speed_y *= -1

                    if self.x1 <= 0:
                            self.__init__()
                            enemy.score += 1
                    elif self.x1 >= SCR_WID-self.size:
                            self.__init__()
                            self.speed_x = 3
                            player.score += 1
                    for n in range(-self.size, enemy.padHei):
                            if self.y1 == enemy.y1 + n:
                                    if self.x1 >= enemy.x1 - enemy.padWid:
                                            self.speed_x *= -1
                                            break
                            n += 1

            def draw(self):
                    pygame.draw.rect(screen, (112,138,144), (self.x, self.y, 8, 8))

    SCR_WID, SCR_HEI = 640, 480
    screen = pygame.display.set_mode((SCR_WID, SCR_HEI))
    pygame.display.set_caption("Justin's pong")
    pygame.font.init()
    clock = pygame.time.Clock()
    FPS = 60
    player = Player() 
    ball = Ball()
    enemy = Player()

    def main():
        while True:
            for event in pygame.event.get():
                            if event.type == pygame.QUIT:
                                    print ("Game exited by user")
                                    exit()
        backgroundimage = pygame.image.load("background.png")
        ball.movement()
        player.movement()
        enemy.movement()
        position = (0,0)
        screen.fill((0, 0, 0))
        screen.blit(backgroundimage, position)
        ball.draw()
        player.draw()
        player.scoring()
        enemy.draw()
        enemy.scoring1()
        pygame.display.flip()
        clock.tick(FPS)

    main()