What can I do next to fix my digestive issues?

A month ago I asked this question about beating some stomach issues I picked up in Mexico.

Basically, I had diarrhea for a few weeks. That part is done now, but my stomach still isn’t back to normal, and it’s been over two months now. I saw a doctor and gave stool samples but they didn’t find anything.

I took a bottle of probiotics (45 pills, twice a day) but it’s still not better. I just started my second bottle, but I still want to take further action.

My symptom now is just that my stomach loudly and uncomfortably churns after eating.

Any advice would be much appreciated! Thank you!