do you have any pepto bismol or keopectate about a tablespoon should do it.
it definatly doesnt taste as "good" as the kibble and bits, and it wont result in technicolor poop but it should get his tummy back on track pretty quick.
we use it for ours (with vet aproval), particularly when charlie decided hes going to knock down the gate for a kitty litter snack...