Uti or implantation?

So I am 95% sure I have a UTI. The burning when you pee, the constant feeling of having to use the restroom and only very little comes out. However, I'm supposed to start my period tomorrow. I am having very light, pink bleeding but I NEVER have spotting before the actual start of my period. Could i be bleeding from my uti? I am sexually active, could this be implantation bleeding? I wore a tampon overnight in case i started my period, but there was no blood. The second I peed though, there was the light pink!