It is interesting how these infections mess with our nervous system. I definitely don't want to say that all your symptoms can be explained by POTS, but brain fog and headaches etc, don't seem far fetched at all.
If your blood pressure and heart rate is all messed up it seems logical to me that you can get weird head symptoms from lack of proper blood flow to your head.
I had POTS like symptoms about a year ago, my LLMD said if it continued for 1-2 more visits(i was going every month) she would officially label it as pots, but basically the table tilt test would send my heart rate sky high and my blood pressure dropped a bit.
Also i would do a test where i would sit with a heart rate in the 80s(already to high) and then stand up and walk in place, within a minute or two my heart rate would hit the 150s (i'm 33).
What helped me with that was exercise and hydration, as impossible as it sounds i started walking, then jogging, then lifting light weights and now i run 3-5 miles about 3 times a week. I occasionally still get really high heart rate early in the mornings, and my resting heart rate is still too high, but i can actually tolerate moderate exercise well.
I would recommend you try the medicine for a while, who knows it might help, but staying active is very important for you neuro system to self regulate.
Have you noticed an improvement in daily fatigue with the amount of exercise you do? I feel so fatigued most days that it's hard to just get the energy to clean the house.