Vibrating sensation and sharp muscle pain in my legs for 2 weeks @ night. rheumy appt on 9/30. what could it be? safe to wait for doc appt?

Muscle spasm: Sounds like a muscle spasm or compressive neuropathy. No harm in waiting. May resolve spontaneously. Light stretches twice-daily may help.

You should be fine: To wait until the appointment. As long as you have not had any long travel and dont have significant leg swelling. It could be any number of things and will need physical exam and imaging/mri to find out what is causing it. Unusual to have rheum appt as first workup? Do you have any other rheum issues? You should be fine until then. Any systemic signs, fever, confusion, etc, get assessed earlier.