hello, for the past two weeks ive been peeing blood, it doesnt hurt during the pee until im almost finished and it feels like a heavy pain, for the past 5/6 days ive been having back pains just where my waiste is, as each day goes by it hurts more and more and now im struggling to walk, ive recently had sexual intercourse also, but when i went to the hospital there was no sogn of urine infection what so ever, is there any way you could help me on what this is? im also 17.