Faint positive this am, negative this afternoon

Amber
AF is due December 12th ish (I'm very irregular)  I tested this am and had a faint positive.  Tested again this afternoon and was negative.  Because it was making me crazy, held my pee for 3-4 hours and retested tonight with First Response digital and it was negative.  My breasts are very sore and I have been more tired than normal.  Something like this ever happened to anyone?? Thanks!