I had pink a couple days ago and now its appearing in my other eye. I don't understand why it keeps coming back, I wash my hands constantly, I disinfected everything and I threw away all my old makeup, so why do I keep getting it?

You. You may have conjunctivitis. Do you use an eye lash curler? If you started using new mascara before the possible infection cleared, it could still spread. Maybe you don't have pink eye. I suggest that you contact your doctor as standard "pink eye" usually clears up in about a week. You may need medication depending on the cause of your eye redness.
It. It is extremely common for pink eye * (viral conjunctivitis) to move from one eye to the other. It may last anywhere from a few days to three weeks. Wait to buy new makeup until it has completely resolved in both eyes. Artificial tears and cold compresses will help with the discomfort. You are correct in washing your hands and using caution not to contaminate others.
Pink. Pink eye is a layman's term for a viral conjunctivitis. It is highly contagious and can easily spread from one eye to the other. Most common mode of transmission from one eye to the other is by your hand. Since you keep your hand clean, it probably spread from your pillow while sleeping or from a towel. However, if it happens often then it may not be a pink eye. Most common condition confused with a pink eye is allergies.