My dogs poop is inconsistent again!

This year has been rough for my 5 year old chihuahua. Earlier this year she was misdiagnosed for pyometra and had to undergo surgery. We took her in because she started acting lethargic and didn’t want to eat. I also noticed her stools were a lighter shade of brown. At the time we were feeding her Nutro Essentials Healthy Weight. During recover we had to constantly bring her back to the vet and they were of no help at all! They didn’t give me any antibiotics for her or anything for her fever. We went to a new vet. She was a lifesaver! After she got better I started feeding her Nutro Essentials Chicken Recipe. Her poops were getting lighter and lighter then eventually turned yellow. The consistency was like mustard. We were given some probiotics and that seemed to help but I decided to switch her food. I started giving her Merrick Healthy Grains. She gets 1/4cup for breakfast then again at dinner. We had no problems with this food after transitioning and she seemed to love it. It’s been a few months and I’m starting to notice her poops getting lighter. She poops about 3 times a day. In the mornings her poops are normal, log shaped. The second one is usually mushy, hard to pick up, and light brown. The last one before bed it’s been half solid, half mush. I’m just wondering what could be wrong? She’s been to the vet and we were given microflora packets to sprinkle on her food. That seemed to help. We don’t have anymore but it’s been a few weeks without issues. Now I’m wondering if the food is making her this way again. I stopped giving her normal treats(sweet potatoes, green beans, bananas, pumkpin, peanut butter) and just give her kibbles as a reward. Doesn’t seem to have helped. Attached is a photo of what her poop is like before bed time. Sorry it was hard to pick up. She still acts pretty normal and does her normal activities.