I think he will be fine on JWB however Argen Grange is a really good food for sensitive tummies too and if you email them requesting a sample they send out a HUGE bag which lasted my 2 forever! I really recommend it but I would just stick with the JWB for a while longer to see if his tummy settles with it.

Edit: Just to add my BSH will eat everything & anything and hasn't had any problems - each is different he may be OK

__________________

My British Shorthair Boy

"Be who you are and say what you feel,
because those who mind don't matter
and those who matter don't mind."
Dr. Seuss

I agree stick with JWB for the moment, see if kitties stomach gets used to it. Cos a change of diet could upset tummy further.

I changed my cats food recently, but back to good old JWB....

Up to you though, you do what you feel is best!