Does anyone have experience of developing an exercise regime when recovering from PCS?

Last month 5 lengths in the pool caused migraines and post concussion symptoms.

Recently on Saturday I was able to walk 2 miles, and yesterday walked 3 miles and did 12 pool lengths. Today I did 10 mins each on the treadmill (walking), crosstrainer and bike followed by 20 pool lengths. This has caused nothing more than a mild headache and earache. I want to push on without provoking my old symptoms. Is PCS recovery rapid when it starts or does it take time? I am being very cautious about exercise because of what has happened in the past, but am growing in confidence.