Welcome to YT!
I'm sorry your princess has been having tummy troubles. I can understand your worry, especially considering what you've been through already!
I don't know as much as many others here do, but after reading posts, and checking out this website:
Dog Food Reviews - Main Index - Powered by ReviewPost
I decided to change Lexi's food to a higher quality food. You can go there to check out the IAMS and look for something that might be better for her.
Good luck, and I hope she feels better soon.