Why wont it disapeared?

Everytime i have , i get this burning pain whenever i p out urine. I went to the doc a couple of times and apart from anibiotics i was advice to drink lots of fluid which i do almost 2lts a day. iv search the net and found that it might be uti. i tend to get it for a couple of days and it's really painfull, apart from cranberry juice isn't there any other things i can do to make it stop.