Nemo needs help!

Nemo is in need of help. Several weeks ago he came in with a slightly swollen eye . We had a vet come who said it was just allergies and slight uveitis. We didn't know we were about to hear bad news and the possibility of loosing him was so real. While his eye was seemily getting better , it suddenly crashed one day and he began to have trouble breathing . We had the ophthalmologist out who said he had a possible sign of a tumor or it could be swelling from infection . We had our vet come back and did bloodwork, ultrasounds, scopes and absolutely exhausted my credit card to only be left with questions . The last scan was of his lungs and abdomen where we did find he has pneumonia, but that whatever is happening to his head is possibly not related. The next step to see what is happening would be a CT scan, possibly xrays and further diagnostics. Which all may point to a tumor or heart failure (although no heart abnormalities have been found on the field scans and exams but doesn't rule that out) id love to get final answers so I know we have done everything we can for a pony who did everything he could for everyone else . 20 years as a school horse who gave hundreds of children wonderful life long memories and confidence . The goal to raise would be around 4500, which should cover his CT scan, the heart scans, and treatments if available and safe for him. I was very hesitant to ask for any help, but I had so many people say I should try as nemo is so loved in the Lexington equine community so I owe it to him to try to see if we can do anything further to help him . If you can help, any amount is beyond appreciated.