Shoulder spasms 3 weeks post-humerus ORIF

I am dealing with some awful spontaneous and light movement-induced spasms in my shoulder muscles. It started last week, got better, and just felt something catch and they started again. Sometimes it's hard to even get up. PT stretching helps temporarily but then the muscles seize up again. Tylenol, ibuprofen and even vicodin do nothing. Other relevant info: started PT 2 weeks ago and have been slung for 3.5 weeks.

Is this normal? When does it stop?