Yeah, mysis is a good food to start and help bring back to health, small food is best, but really light is their main source of energy.
I wouldn't even worry about spot feeding at this time, give it a week or so, let it settle.
Don't turn pumps off if foot is set, it will need to find a spot where it is happy w/ the flow, so if pumps are off, there is a good chance it will move when you turn them back on.