Period Probs... Someone help!

So... I've been on the pill for years. Never would I have thought I'd have issues with it. Recently I've been missing my period the past two months I have had horrible PMS symptoms around that time of month and NO PERIOD. Every month before I ALWAYS had a normal period. I'm starting to get really freaked out. I've taken like 10 pregnancy tests and all come up negative. I have no clue what's going on and my OBGYN can't see me until next month. Can someone please help a girl out!?? Lol thanks in advance!