OmaJ

I was experiencing this when I was eating sugar (cookies, cakes) and starchy carbs (bread, pasta, rice). I eliminated bad carbs and increased vegetable and no longer have gas and stools are normal in color.

C. Diff. is a possibility, but from personal experience I think you would know if you had it. It is more than just loose, runny stool. It was extremely painful and miserable. Probiotics help, but there is no getting over it or lessening the symptoms unless you are given a very specific antibiotic after giving a stool sample. If they gave you a Z-pak or amoxicillin, it would actually make C. Diff worse.
For gastric bypass the foul gas and BM is normal. As I understand it, it is because of the partial or incomplete digestion of food that causes it. I'm sure it seems bad now, but it get better over time.

Ask them to test for C. Diff. A bacteria that causes runny, foul smelling stool

Welcome.
If you felt that much anxiety after seeing the scale jump by 3 pounds, perhaps it is time to weigh yourself less frequently. Try weighing in once weekly, or even once a month.
Realistic expectations are important. Weight loss with a sleeve doesn't occur in a neat, linear pattern. We lose pounds, then stall/plateau on occasion, then may even gain pounds due to fluid retention or glycogenation before dropping weight again.
When is the last time you lost 14 pounds in 2 weeks through diet and exercise? I'm guessing your answer is "Never."
You're doing great. Stay off the scale and allow your body to sort through the trauma it has experienced. Expecting to lose a pound a day is unrealistic.
Good luck to you.