Thank you, Lizzie, for the good thoughts and some more good suggestions and ideas. I'll also run these by the vet.

I give Sydney 125ml of fluid every day. I've been giving him this much for at least a year and before that 100ml for a long time.

Sydney hardly ever throws up (though someone else does from time to time.. I'm not sure which one or if it's only one, since I haven't caught anyone in the act).

I'll keep you posted! Thanks again,

Sydney and Pat and the gang