If you truly repaired your metabolism, it should see you through a short term hiatus from your usual exercise routine. At least, that has been the case for me. I am afraid that if you drop it too low you will do just the opposite and it will backfire by hanging onto those extra pounds.
As for doing cardio. I have advanced arthritis. I have managed to find water aerobics as calorie burning as the old 11 minute walk I used to do! I also have exercising designed specifically for those who are mobilely challenged. I remember Richard Simmons once saying that if you want to raise your heart rate, raise your arms higher and faster. If you need to lower your heart rate, do the opposite. I think, you can get a lot out of sitting in a chair and "dancing" with your arms and upper torso. In fact, swing your legs around too. Just watch the sore foot. I think you'll do alright.