Probably won't make you feel much better, but rectal bleeding is one of those things that is often from a completely harmless source......hemorrhoid or lacerated bowel wall secondary to hard stool. It needs to be investigated promptly and throroughly, don't get me wrong, but in a young, otherwise healthy person it is very often caused by something with very few or no long term health implications.
Second opinion in this situation will likely not help out here....besides, her PCP will almost certainly consult a gastroenterologist or general surgeon; standard of care, IMO, for 1st episode rectal bleeding is colonoscopy. (Some might wish to debate that, I suppose.)
BTW, I don't see rectal bleeding listed anywhere on the P.I. for Ketek. Could you cite the website(s) where you found a reference to rectal bleeding and Ketek?
Best of luck to you and your GF.