Yikes! What a horrible ordeal with the wormer!
I'm glad to hear Zack is doing a bit better with the chicken and rice. It was a big help for us with Pixie and her extremely sensitive tummy. What Karlin recommended is exactly what we did, slowly increased the amounts we were giving her. After that seemed to work, we started adding a few pieces of kibble, giving that a few days, and if it all stayed ok, adding a few more.
We also started giving her a probiotic pill every day. We use Gentle Digest from Ark Naturals, but there are several brands that others use.
Another thing I thought of is to wait a bit (like 1/2 hour) after the pup eats before they play hard. Pixie only had a short spell of vomitting, but during that time, it seemed to help.
Pixie's system still does not tolerate drugs well, we know every month when she gets her heartworm meds she'll have a day of soft poops, but we now know to expect it.
I'll keep my fingers crossed for you that things continue to improve.
Mom to Pixie - DOB 5/27/04
And rescue kitties Max and Sophie