We had a mare at our barn with a few broken ribs from a fight she got in with another horse..it was just time that she needed for it to heal. We all thought she would never make it back, but she's really as good as new.
I don't have any advice, but sending jingles your way for a quick recovery!
i had a horse with broken ribs, after a fall, the swelling if there is one can go to the lowest point of the body which is the chest you need to monitor the horse daily
as he could need antic botics to help get rid of any infection,
has the vet prescribe him pain killers for a bit as he should have them now bute helps to reduce any inflamation as well as reducing any pain issue
box rest for a few days then if you have a sick bay paddock or small area where he can go into would help, so he get minium exercise small grass area or section part of a field for him with plastic poles elecy tape and enigizer
can help the area ice clay its meant for areas you cant bandage and it easy to apply and wash off
light diet and no high energy feed stuffs plus easy to diagest feed stuffs
big beds and banked sides will support the horse if he choses to lay down and laso help get back up so he doesnt get cast
the healing process can take a couple of months or more depending on the injury
obvously when bringing him back into start slow and have the horse on the lunge without tack then with so he get re acustomised with the saddle and girth
before a rider gets back on him