I hate having to give my cats Metronidazole, it's so very bitter and you begin to wonder if the side effects aren't worse than the reason you are giving the med.

None of mine have ever had diarrhoea after the Convenia shot, though they have after some oral antibiotics.

Have you tried putting cooked pumpkin in his canned food as someone else suggested. It comes highly recommended.

I'm sorry you and Albert are having a rough time and hope he gets better soon.