A change in protein might be a good idea. Chicken turns out to be frequently allergenic. One of our dogs is allergic to chicken and we switched to pork.
We've also used Drontal with good success, although it does tend to make them hyper for a few hours after they get the pill. We've never had to use it on a dog with another major medical condition, though.
"We are--each of us--dying; it's how we live in the meantime that makes the difference."
"It's not what you gather, but what you scatter that tells what kind of life you have lived!"
"Be kinder than necessary, for everyone you meet is fighting some kind of battle."