Pain and tiredness in right leg calf muscles for last 8 months?

I am 23yrs,72 kg,174cm.I used to jog 5KM in park everyday,bt suddenly 1 day in morning i got pain in right leg below knee.doctor said it's cramp,gave cream,bt no relief.Then i undergone ultrasound for DVT,bt everything came normal,doctor said there myt be muscle pull and gave medicines.Bt it's been 8 months bt pain is not going and when i walk for 2 Km continously my right leg starts tiring,little bit heavy and painful also.Please help soon.I am worried