My macbook’s screen is flickering and has pink lines running through from the top to the bottom? What to do?

I hope you have AppleCare +. You'd have to make an appointment at your local genius bar and take it in for evaluation, or if you don't have an Apple store near to you, your local Apple Authorized Service Provider., anyways, you'd have to see what they have to say. Probably a repair will be in your future

john b