Reptile & Amphibian Forums

I recently purchased about a 4 foot field collected Gonyosoma oxycephala, (Red tailed green rat snake)
The snake was sick when I received it with RI and internal parasites. The vet wanted $300 to treat which I don't want to spend on this particular animal. He gave me an RX for ceftazidime to inject myself but I could not find a legitimate source for the drug.
I treated the RI with F10 nebulizer twice daily for 2 weeks and it seemed much improved. I force fed it a hopper 5 days ago and 3 days ago I gave it a oral Panacur dose. I did not have Panacur when I fed him or I would have injected the mouse.
Today I noticed the room he is in smelled like snake feces but no mess in cage. He is keeping his mouth open more than just a yawn, and occasional having a fit, flopping and twisting around his enclosure with mouth open.
Is it possible the RI is returning or is there something else I maybe missing? Any advice is appreciated.

Snake died.