What Does Pain In The Right Foot Indicate?

Two weeks ago I started having pain on the right side of my foot while walking. An X-ray revealed swelling and inflammation and the doctor said it could be a hairline stress fracture or Tendonitis. I received a steroid shot and have been trying to keep my foot elevated, heat, etc. On the same foot, on the outer edge close to the pinky toe, I had what I thought was a blister. I just put a bandaid and the blister is gone, but that area is still very painful when trying to walk. The outer bone on the side/ bottom of my foot feels tender, but it’s not broken. I had been walking more than usual when the problems started. I at first thought it was new Nike’s, which I’ve been told by many people , including the doctor, is not a good brand for walking/ running. I bought New Balance a week later, which seems better, but I already had the foot problems by then. It does seem odd that it’s just my right foot though. Sorry so long.