A little bleeding?

Here's what's going on. For starters, I think I may have a UTI. I have a little burning while urinating. Today when I wiped I noticed a little bit of what I am uming is blood. Is is really light, almost like when your period just starts. More pinkish than red. I am also on Loestrin, this is my 3rd cycle while on it, and I am at the end of week 3 on this pill pack. I have not had breakthrough bleeding at all when on it. I am technically due to start my period on the 17th. I am also having some mild cramps. Could it be related to the UTI, or is it breakthrough bleeding? Or any ideas on what else it could be? I am just worried because I have never had the breakthrough bleeding before.