What are the chances of my repetitive stress injury being completely permanent?

Low. Usually it can be treated by meds , therapy and activity change. We still don't know what stress injury you are referring to. We are here to help so the more info we have the better our answer can be.
Can progress. If you do not take care of the pain this would progress and start developing muscle atrophy and loss of strength in this area - you need special wrapping - manual lymph drainage and complex decongestive therapy it would be offered at local physical therapy clinics they also have lymphedema diathermy which might help.