I am 43, female. I have gained 70 lbs in the past year n a half. I don't eat out. I cook. I don't drink. but do smoke. when I go out and begin walking, within 2 minutes I get sever pain in my legs. not calf, in the front shin. both legs. once I stop, wait a few minutes I can continue. is it just the weight gain, or do I need to see a doctor