I must have misunderstood....I thought you could not remain conscious when upright. I also thought that the pooling was visible and that your feet turned purple. That would have indicated it was very profound. Perhaps it is POTS.

If it is POTS, then, medication and trying to retrain yourself to remain upright could possibly get you moving again. I was quite immobile for a while, but, forced myself to get moving and was slowly, and I mean really slowly able to get going again.

I think I was sick for a long time, but after I had a surgery with a general anesthesia, it seemed to me, that things accelerated and I spent several years really incapacitated. I am slightly better now, well, some what better and can be up for fairly long and can be active.