Hello and welcome to the boards! Hopefully, you will get some other responses, but I’m actually more familiar with muscle *weakness* as opposed to muscle *pain* as a symptom of Graves’. Muscle weakness is quite common, particularly when hyperthyroidism goes undiagnosed for a period of time. Patients can have a hard time with simple tasks such as walking up stairs, getting out of a chair, or holding their arm up to use a hair dryer.
Muscle *pain* can potentially be a side effect of PTU, although it sounds like you were experiencing this issue prior to starting on the PTU.
It *is* possible to rebuild muscle strength once levels have stabilized, but it can take some time and patience. If muscle weakness is a significant issue, a physical therapist might be a good addition to your medical team.