Hi there. Sorry to hear your baby isn't feeling so hot. I don't know if this will help, but my lil Sunni had terrible tummy issues when I first got her. It was a combination of issues so finding a solution was really difficult. Her problem was mostly loose stools, and I did use the canned pumpkin which hardened everything right up. I did start adding organic plain or pumpkin yogurt to her diet every morning and a bit of organic coconut oil. About 2 tbls of yogurt and a tsp or so of coco oil. Its made a huge difference. She has perfectly normal stools now and no skin issues.
Its probably a good idea to run this past your vet, though my vet approved of this
Also, I agree at this point she may need to be on a prescription diet food. Good luck!