I Recently (2 Weeks Ago) Was On A Plane For

I recently (2 weeks ago) was on a plane for 18 hours, and didn't get up. I noticed when I got home the next day my left ankle was a little swollen, but not painful. Monday 12/12 I started a challenge with some friends, we drank 1 gallon of water a day, but everytime we went to the bathroom we had to do 25 squats. I did it for 3 days straight working up to about 200 225 squats a day. I did them at work and wasn't wearing proper shoes, into the 3rd day I stopped because I thought I developed a shin splint in my left front leg, then it moved down to my ankle on the side, swollen, warm to the touch, and pain full. Went to ER last night ruled out DVT, and took xray, I can't have an MRI due to having a pacemaker. I regular exercise but within the last month I've slacked off due to recovering from hysterectomy. Could this be a stress fracture, I am over weight but very active. your thoughts ?