Seriously need help!!

So we aren't trying but not preventing at all (so yes trying). I just had my period and it lasted the full seven days, however, it was different. I normally have really really bad periods, lots of clots and extremely heavy. This period I would say was a normal period for people who don't experience heavy periods.

I took pregnancy tests before my period and all came back negative. And when I got my period I thought that was it.

My "Period" ends and my husband and I have sex. The next day I have a weird discharge I have never seen, it's was like stretchy clear and then white creamy. Now one of my breast hurt and I keep having headaches.

Has this ever happened to anyone?

Could I be pregnant, or could it be a chemical pregnancy?