Flank Pan....Pain on my left and right side

I've been having problems with my side for almost a year, i have had all kind of test take and they have came up negative. I don't know what to do or where to go to for help. I'm constantly going to the Doctor or convenient care and they keep telling me the same thing, bladder infection or uti. I am at my wit ends. I am constantly in pain and i don't know what to do. I know something is wrong with me but what. Can anyone please give me some type of advice or something.