Just a scare?

I had intercourse on 10.18.15. Which was 4 days after my period and the <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">period tracker</a> I use says that my fertile window started the day after. I usually don't ovulate that soon after my period but my period started earlier than it was supposed to so idk. About 2 weeks ago my breasts started to be really sensitive& achy. They still are now. I've had a few dull cramps on and off for about 2 weeks and I was having a bit of queasiness and discharge for a while but now it seems to have subsided. My tracker says that my period should start tomorrow but I just don't feel it coming on. . Any thoughts?