I think it's probably just weight related and nothing too serious. When I was 220-230lbs I couldn't hardly walk for 15 minutes straight without my feet starting to go numb, and now I'm a lot lighter, I don't get that problem at all.
But if you want peace of mind, then definitely go and see your doctor; it can't hurt
As for exercise, just continue what you're doing and only do as much as you can without it being too painful; I bet as you start to lose weight it will ease up. Just don't feel like you need to do strenuous workouts straightaway to see results; any movement will help. GL!