Swedish DJ announces "I could be back ...but I won’t be right back."
Festivalgoer says he was beaten up before being found near TomorrowWorld in Georgia
Swedish DJ is still suffering issues related to surgery earlier in 2014
Swedish EDM star also has Serj Tankian and Matisyahu on board
More than 30 patients were taken to hospital with more treated for dehydration on-site
Most were suffering from the effects of alcohol
Deadmau5 will replace Swedish producer at Miami event