Hang in there. Based on my experience with my own and those I did not kwn but knew very well? Odds are you will be dealing with these until you grow a healthy foot…like…a year. One example of when to spend up on a proven hoof supplement that really works and start with a double dose. It will still take time but at least the body has the building materials to work with. Malnutrition is more than just skinny. Even expensive horses in good weight can lack proper nutrition and have crap, abscesses prone feet.
Biggest issue, besides time, I ran into is the horse has to move to allow the hoof to flex and pump the crap out and standing as much as possible lets gravity help. But the horse that is really hurting will do neither. Then we want to let the fever in the foot go so the abscess can blow out, but the horse is really hurting. What to do?
IME, give them something for the pain. Several good options out there including good old Bute. Given CORRECTLY for a short time helps with inflammation and pain relief so horse will stay up and move more.
Are you soaking yet? Epsom salt, preferably in warm water, Ideally pack with Icthamol (sp) and wrap but you can skip the wrap if he wont tolerate it.
Poor guy, least its only in the one foot. For now but be ready for more. He’s is still very much a baby who has had a rough time. Remember TBs can be less stoic then other types more suited to a rougher lifestyle.