POTS and Ropineral

Before I was diagnosed with POTS I was diagnosed with Restless Limbs. That obviously didn't explain the POTS symptoms, but my then neurologist didn't know what that was. She put me on dopamine agonists. I tried several different ones, but each had major side effects. But what really didn't make sense was that they made the symptoms of POTS stop. The doctors I see now for MCAS and POTS assumed that they would have made the symptoms worse, but no. Ropineral was the one I tried to tolerate the longest, but it was making my sinuses close up for over an hour every time I took it, and it made me nauseous, so I stopped it.
I am taking metoprolol now but it has become less effective since I got a virus two months ago.
Can anyone explain why dopamine agonists made my POTS symptoms stop?