Paint for bathtub/shower area????

I live in an old house, and can't afford to put in a new tub ours has awful iron stains that I have scrubbed literally for hours at a time. I wanted to know if there is a paint that I can use to paint the tub, and also one for the shower area??? I got the porcelain repair kit but I haven't used it because you can't use the shower for 4 days or something like that and we only have one shower.... Any help would be appreciated

Katrina