Chinchilla
...
This is OP's first horse, if I remember rightly, so it's worth remembering that most people don't expect - and consequently don't prepare for - anything like this; certainly not with their first. I feel quite sorry for OP to be in this situation, but agree that at this stage a hospital referral for in depth investigations would probably be the best root as the horse's quality of life, in my opinion, needs to take precedence over anything else.