Hi there, and welcome!
If I were you I'd just give her the chicken (any chicken really, if it's only for a short while it doesn't matter which parts you give her as long as it's got meat on it) without boiling it at all - same goes for the fish. If she will eat it raw, this is much better for her than boiled.
If she won't eat raw, try just cutting the meat up in small pieces and plonk them in water to boil for a very short while - try to keep the pieces raw on the inside. Don't add any spices, salt or such.
I'd also recommend you do a search on these forums, there have been plenty of threads on cat food and upset stomachs which may help you.
Good luck
