I recently started birth control for the first time to help with unbalanced estrogen levels. I ve been on it 8 days. 2 days ago, I started having a dull ache behind my left knee/lower thigh area. Today (for the last 5-6 hours) I ve had a persistent left calf cramp/pain that s about a 7 out of 10 on the pain scale. Ibuprofen, a hot bath, and heat and ice compresses are not helping. My leg has no signs of swelling, warmth, or discoloration; just deep calf pain. Could this still be a blood clot? Should I go to the ER tonight?