My muscles started seizing up in my back and neck since the POTS symptoms started 6 years ago. Wondering if this is common? Prior to 6 years ago, I had no tight muscles (except neck when sinus headaches accompanied), no heart race, no dizziness, no gastro symptoms and no chemical sensitivities and no MSG allergy. All started at once. Most can be remedied with salt tabs and lots of fluids. The muscles that seize up are a problem.