I would continue with the exercise but see a podiatrist to see if there is something wrong with your feet. My son had severe leg pain for the first 7 years after he started walking. They did x-rays, tested him for leukemia, and did a lot of head scratching and suggested growing pains even when he wasn't of an age in which they should occur. Finally I took him to a podiatrist who fitted him with orthotics. He says not only do his legs feel better, his feet and knees do too.

Perhaps that's not your problem, many things can cause leg/foot/knee pain, but it would be another place to look. We saw a pediatrician and two family doctors who never considered the podiatrist.