I went through all that you have described & more for over a year without any results from any specialist doctors. I just found out I have high markers for autoimmune disease. But I started treating this issue of swelling naturally as NO dr. could get swelling to go down & had no clue why all the swelling. I had to heal something that was going on in my stomach to get some of the swelling to go down. After getting on protien shakes, going on a strict diet of no red meat, no dairy, no bread & taking large doses oil of oregano & grapefruit seed oil + flax seed oil, I can say I am finally feeling about 85% better. It was a long process & i refused to take the Malaria medicine the RA dr wanted me to try, I also did not take any antibiotics, etc. to help cure myself. I am not saying don't do what doctors want but be careful.
Also, look into fungal infection in sinuses as this can cause the swelling. Getting a functional med. dr involved is a great bet your son may heal a lot faster. That is what I did. I am so sorry you have to watch your son struggle but please FIGHT for him & I mean be DEMANDING & PUSHY as you can. I had good doctors say they did not know what to do for me & I thought I was going to die. Please call in a funtional med dr or natural path dr.