I suppose IBD is a possibility but it needs a biopsy to diagnose

Has he been tetsted for tritrichomonas foetus, this does not show up on standard faecal testing, needs a special test. See TFFelines.com - Home

Some people find that Iams Hairball dried food can help in cases of diarrhoea where nothing else seems to work - it has to be fed exclusively (no other food offered) and will work within 2-3 days if it's going to.

Other people swear by a raw diet for treating this type of problem.

I can understand how frustrating it must be, as well as unpleasant for your cat and you. Hope you get it sorted soon.

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