Doctors can't give me an answer.Does anybody know why this is happening?

You need to have an ultrasound of the veins in your legs. This is the only way to determine if you have a blood clot. I would consider going to the ER. DVTs can be life threatening. If you can't get to the ER (which you SHOULD!) then call your PCP and have them send an order for the ultrasound to your local radiology clinic. The fact that you are having chest pains is worrisome. Please go get checked. Especially if the pain is accompanied by redness, swelling or warmth in the calf, pain when you flex your toes back toward your body, or difficulty extending your leg.