My inner eye on the bottom waterline is swollen and very painful to the touch. t's a little red too and itchy. what could it be?

Possibly sty: You may have a sty or blocked oil gland of the eyelash (gland of zeiss) that is secondarily inflamed or infected. Try mod. Hot compresses 2-4 times/day for about 10' followed by gentle massage with diluted baby shampoo on a clean washcloth. This should help it resolve in about 7-10 days. If not and persistent or worsening, then an exam is needed to verify the lid lesion.