If certain MWODS make something numb based on your situation you shouldn’t continue to do it. As Kelly notes
If it feels sketchy by all means don’t do it.

What is causing the overhead impingement?
You don’t want to mess with something when nerves are involved.
Have you tried using something other than a lacrosse ball? One of the YTU balls, a tennis ball?
If you think you are injuring yourself, STOP. Don’t over do it. More is not necessarily better.
Have you considered seeing another doctor or PT to have another look at/opinion on what is going on?
Yes, the recovery process can be frustrating, but doing things before you are ready can cause more problems down the road.