That could be your problem right there. I didn't know anything about that food, but after looking it up I did see a lot of complaints mainly cheap fillers. You might try changing to a good quality food and start giving a good probiotic
Are you sure your dog isn't allergic to chicken? That could have been the problem the first time around. Maybe try a small turkey, and no about cooking the sardines, I buy the ones with no salt in spring water .
There's a thread on here with the different dog food ratings. If you're going to do kibble I would stick with the better ones, nature's logic, open farms and some others, avoiding corn and other fillers.I rotate the proteins with every bag avoiding chicken.
Royal canin is full of corn meal and fillers plus the chicken can also cause allergy problems. Unfortunately Iams isn't much better, personally I'd look for healthier options. Can save you down the road in vet bills. Beautiful pup
Congratulations on your new puppy. I'm sure you've seen the link on here about food recommendations, the only negative I've heard about orijen is that it was bought out by mars and there was concern about the recipe being changed. Most on here will tell you that raw is best but the decision is...
No Purina, science diet or royal canin. All will say raw diet is the best. You can look on here for quality kibble choices. Personally I go with open farms ancient grains, I don't do the chicken or beef and I use their freeze dried raw as a topper.
I'm sure some of the others on here will know more, but yes the amoxicillin could be the cause of her diarrhea. It can kill the good bacteria in her gut. Try giving her a tablespoon of pure pumpkin puree not the pie filling 100 percent pure.