Ehlers-Danlos Syndrome Support Group
Ehlers-Danlos syndrome is a group of rare genetic disorders caused by a defect in collagen synthesis. Depending on the individual mutation, the severity of the disease can vary from mild to life-threatening. Common symptoms are unstable, flexible joints with a tendency to dislocate and subluxate, and elastic, fragile, soft skin that easily forms welts and scars.
I would say that it is probably being caused by the Celebrex, and maybe there is another med they could give you to try. My concern is that the muscle movements are called dyskinesia, and they can be permanent if you don't stop the meds. So, I would certainly talk to the doctor.
Good luck! I don't know about the POTS part though. sorry.
It's easy to google any drug and find a list of common side effects:
http://www.drugs.com/sfx/celebrex-side-effects.html
Sometimes doctors don't pay attention and so every patient should be active in this.