That is a mycroplasma infection of the respritory system (Chronic Respritory Disease) The eyes swell because the sinus cavity runs under them. It takes a few week to get them over it (no quick cure) and it is very contagious. Tylan is great for it, as are all tetracycline based anitbiotics. Get them all on some very soon. It can kill in bad cases, especially younger birds like that.
Tractor Supply Store often have the Tylan and others on hand, or you can order on-line at Jeffer's.com
There seems to be a run on it in the colder months, I guess like us, we get colds worse in the winter too, and that's basically what this is, a poultry cold.
Survivors of it often end up being carriers of it, so dont be suprised if it pops up later again down the road, always will be good to have some anitibiotics on hand. If you even suspect one looks to be getting it again, give them a few days treatment and it can often be stopped earlier before another out break occurs. Oh also, watch the eyes, I have seen it mucus build up in them and form hard nodules under the eyelid. If you notice this, gentley mash it out from under the lid and remove it all. If left in, it can permanetly damage that eye or just out right put the eye out from all the presure build up.
Dont worry though, It's treatable, just takes a while, about when you say, THEY ARE NEVER GONE GET OVER THIS, they end up just fine...
Good Luck