Left leg hurts/ burns. Any help?!?!?

So two days ago I went to the er with chest pains, had a full workup, blood work, EKG and chest xray. Everything was fine, well yesterday I started getting burning pains down my left thigh, and now today it's sore and hurts. I'm terrified of blood clots. I've never had one, none of my family has, no risk factors except I smoke. I'm 23 and have had four negative ultrasounds on my legs in the past, am I just being paranoid?