Suggest Treatment For Pain In The Calf Of Left Leg

I am a 72 year old male. I am overweight and live sedentary life style. I have type 2 diabetics. My problem started about 18 months ago. I started walking every day and felt great, but after about 3 weeks, while walking, I got a severe pain in the calf of my left leg. I didn t think I was going to be able to walk back to my house. I rested after I got home, but the pain didn t go away. When I would get up and walk on it I had to limp it hurt so much. It took about 2 months before I could start walking again, but two days after I started the whole thing started all over again. I was down for another month before I could start walking every morning again. This same pattern has taken place about 4 or 5 times only now it hurts in both legs. Doctor took tests when this first started but they couldn t find anything wrong. What could be the possible and the likely cause. Thank You.