Charly horse symptoms and conditions

I have taken Ovcon for the past year. I do not smoke or drink. I have normal blood pressure, cholesterol. I am 27 years old. I do have a low iron count. About three to four weeks ago I woke up with a Charly horse in my calf. The pain slowly grew until I was limping. I went to ER and they said it was probally a sprain. A week later the pain was so bad I was could barely walk. I went again into the ER and they found a blood clot (deep vein thrombosis) in my thigh. Dr's said it is possible the pill is related since I had no pre-existing factors. The only birth control I will ever use again is condoms.