period 2 weeks early...HELP! (possible tmi)

AF came on 6/30/14. next cycle was due 7/31/14. on 7/18/14, i started cramping and spotting, which turned into full blown AF, minus the clots... i suffer from endo and have been ttc for close to a year now...has this happened to anyone else? can anyone tell me what this is? and since i had, what i assume to be af, 2 weeks early, should i still be expecting it on 7/31? any feedback would be appreciated