Is it a good idea to have medical massage treatments at the same time I'm in physical therapy?

That will be up to your doctor. Sometimes the thing that generates the most improvement is doing both at the same time. Just be sure that your PT appointments are not on the same day as your medical massage appointments, or your insurance company may choose to not pay for one or the other, and it may be several months of regular treatment before you find out your insurance company won't pay.