Hi Kelly,
I had the same exact problem a few years ago. I also tried several different birth control pills. I went and had some special test done (I'm sorry, I don't remember what it was called) and a specialist said it most likely had something to do with the enzymes I took and being on the pill. I can't remember the exact explaination, but he had seen an article about it before my appointment. I quit taking the pill, and it went away almost immediately. I've never had the problem since.
I hope this helps!
Erin
26 w/ CF