Looks like fin biting.. poor fella.
Don't use AQ salt on him, it's not needed and the added stress of the smaller container and daily 100% water change may be too much for him at this point.
If you have a home for him set up, go ahead and place him in there (with only water conditioner) and leave the light dimmed for the few hours after so he can calm down.
Afterwards, I would just leave him be, offer him food daily and not disturb him until it's time to do the weekly water change (you can turn on the lights after the initial adjustment period)- once he is settled he may stop biting his fins. But for now, the more stress he is under, the more he will keep getting at them. So, the less you do, the better for him at this point.