When I was in college, I exercised a lot. I used to jog for an hour and swim for half an hour daily. All of the sudden, I developed pain in my feet and ankles. It was a persistent ache that continued for more than a week. I remember having trouble sitting through the lectures despite taking pain relievers.
The doctor did not find anything after my examination and concluded that it was probably tendonitis. She told me to stop jogging and to rest for several weeks and keep taking pain relievers. I followed that and the pain disappeared. At that time, I had not heard of stress fractures, but now that I think about it, I think that might have been the problem.
I think the symptoms of tendonitis and stress fractures are similar so I don't know for sure. And I never got a CT scan or anything. I do think that some forms are exercise lead to stress fractures more than others though. After the recommendation of my doctor, I have stopped jogging altogether and only swim. I have not had a similar problem since then.
My doctor had told me then that swimming is the only exercise where there is no pressure applied on your skeletal system. When we jog, each time our feet land, the entire weight of our body is pushed down into our feet. For someone who already has week ankles or weak knees, it's not good. That's why I'm going to keep swimming. I can swim until I'm 100 and I won't have to worry about tendonitis or stress fractures.