Hi whenwillitend. I also have a sore ankle/foot with tendonitis, so I can relate to your situation.

Could you help your son build a "fort" or "tent" with kitchen chairs pushed close together and blankets over the top? You could get on your knees, so it shouldn't hurt your foot too badly and it might keep him busy for awhile.

Your son sounds like a very good kid and you sound like a great Mom. I hope you heal quickly. slow