I think that Florinef might help you to feel a lot better.
Florinef is very different than Prednisone, it is a different type of steroid (mainly mineralocorticoid), it doesn’t have all the horrible side effects of prednisone and usually it isn’t immunosuppressive.
The dosage for POTS/NMH is very low 0.1-0.2mg.
From my experience the effect of increasing the fluids and salt intake is very limited without the Florinef. Florinef increases the fluids retention and does the difference.
It might take time to adjust the dosage, sometimes it is necessary to add other medications as midodrine, beta blockers, etc..
It took me about 2 months to find the right combination. During that period I had to monitor closely my HR & BP and try miniature changes of the meds.
It is important to monitor the potassium levels, because Florinef might affect it.