Hi , I'm James DVM MRCVS and would like to help you with your question
First let me ask:
1. is storm vaccinated
2. has there been any improvement since first starting the AB and what type is he getting ?
3. is he fine in himself , eating and drinking ?
4. can you think of something that might have brought this about (eating a something he shouldn't have for ex) or has it come about spontaneously?