weird discharge??

I had unprotected sex about 2 weeks ago. I am on birth control but I waited a little too long in between packs to start the pack I just finished, I'm scared that the birth control may have stopped being effective. I just finished my pack last night and am expecting my period, but after working out I found an extremely thick clear/white discharge. Google has me going crazy because it says discharge can occur during a missed period. Help!!!