I Had A Pulmonary Embolism In Dec 2009 At Age

I had a pulmonary embolism in Dec 2009 at age 40. After multiple tests the only cause they could come up with is the recent birth control pills I had started taking. I stopped treatment 5 months after as I moved to another state for a job and thought I would be fine (no blood disorder found). I have been experiencing difficulty breathing since July. It came on suddenly and I thought I was allergic to something. I have difficulty breathing when I lay down and try and sleep at night and after laying on my back for a period of time I feel a strange feeling like something is in my lungs felt through my back. I have no idea what type of doctor to go see but I am worried about getting another one and feel I need to be looked at. Please advise

Thanks,
Jeanene