My advice would be to avoid exercise, especially if it causes headaches or fatigue. A gentle walk is the best exercise for now, because strenuous exercise delays recovery.

Your body and brain are under enough pressure already, without adding more stress.

I also tried stationary bikes, crosstrainers and swimming but realise now they could provoke symptoms. This was all well intended, but was unfortunately counter-productive looking back.

All I do is walk, because people shouldn't exercise until ALL symptoms have gone. I am at the end of my PCS journey but am still very reluctant to hit the gym in case I go backwards again.

I share your frustration, because I went to the Gym 3 days a week. Patience is the key to recovery unfortunately!