holes in the soil will help. I dunno on the air stone, seems that it might be tricky to get it in there well without some serious root damage, and pumping air directly in could dry things too quickly, which can cause major damage to the roots. Personally I would make sure you have good airflow, maybe poke a few narrow holes with a screwdriver or pencil, and give it time to dry out properly. If you could safely put more drainage holes in your pot it would help, but often that is difficult when they are in use. Hope my thoughts help. Good luck and hope they recover!