The sooner you get him to a Vet, the better the outcome.....Everything I can think of is treatable if caught early...You need to head that way! Please come back & let us know how he is...Don't wait any longer.....
I agree, there are several quite serious but treatable conditions this could be ... your best friend needs to be seen by a vet, sooner rather than later.
Tony
No way to tell for sure but sounds like you better get him to a Vet to be checked out and soon!