Yes. It sucks. Make sure to stay hydrated and be mindful of getting up. When hydrating though, be careful not to wash out your electrolytes. My kid is ordered to salt load from his physician due to low blood pressure. Also, fludrocortizone helps to keep the b/P up.

Dysautonomia International (I think - foggy brain lol) has good information. Typically with POTS there can be more than one dysautonomia going on.

If your fingers bend more than others or have been called double jointed you should look in to Ehlers-Danlos syndrome. Even though it is a genetic disorder, I did not get diagnosed until in my 40's.

Must are misdiagnosed with mixed or undererentiated connective tissue disorder and fibromyalgia.

Pretty much you know you have it if a doctor says something like "Wow, you have great range of motion, I have no idea why you are hurting, your x-rays look fine."