Bella is a 4 year old mix (looks mostly like a boxer, weighs about 80lbs)
I've had her on what I've researched good food (Taste of the Wild) but she's had on and off diarrhea for months. It's so random, 2 months no issues, then randomly gets it for a few days. I have to fast her then start her on rice, etc until I put her back on her food.
I have an appointment with the vet next week but I was looking for some suggestions here. She's not getting into anything in the house or outside so I really don't know what's causing it.
My GSD has what I consider a super sensitive belly. When he was a little under a year old I had him treated for Giardia for those exact same symptoms. I think it was dose once and then a few weeks later, very easy- might be worth a look? Whichever TOTW you're feeding, you may want to switch up and change the protein source. Mine does the on/again off/again thing with chicken, beef and lamb it seems. I have him on BB fish and sweet potato and he hasn't done it since (over a year). Good luck getting him figured out!
Our Lab mix also has what the vet finally decided is a "nervous stomach." She would be totally fine for months and then all of a sudden have terrible diarrhea or vomiting for a day, and then be totally fine again. She never lost appetite, and could eat just about anything otherwise and not get sick. We tried all different types of food to see if that was the issue, did blood work, etc and came up with nothing. We finally connected that it seemed to happen when there was a big change in her routine or something that stressed her out. I don't know if she's mellowed as she's gotten older, or if we've been better about managing it, but we haven't had an issue in the past year or so. The vet did prescribe some meds that we keep on hand to give if she has an issue. It was the worst when she was 2 to 4 years old, which was incidentally right after we moved to a new house.