Never ending af?

I hope someone can help me out. I have had a very long period for the last few months. First it was 10 days, then 12, then 14, now I am on day 18 and still bleeding. I went on the pill this month to hopefully shorten the length of my period...unfortunately that didnt work, as a matter of fact it seems to be worse. I am on lamictal for seizures, but have been told that that shouldn't effect my cycle. Previously I was on dilantin and my cycle was also all screwy. I had pain in my lower right abdomen, aroung where my right ovary would be for a few days, and then one night it got pretty bad. I went to the ER in the morning, and they didn't find anything, and the pain stopped soon after I actually got in a room and before I was seen! No ultrasound was taken. They did do a internal exam and found nothing unusual. My last pap, about a week or two before my last period came back normal.

So any ideas as to what is going on? I'm wondering about fibroids or ovarian cysts. Anyone have any experience with these?