For the next short little while, consider doing a BRAT diet.
Include some bone broth (hopefully from pastured cattle, or store bought organic in powder form) and probiotics of the best quality you can afford.
After your system, settles down some, you can do a food elimination, which is going to take a long time.
If I were you, I would first cut out wheat and gluten and if you are tough-minded, cut out dairy as well at the same time, since these groups are very high on the sensitivity list.
Also 50% of people with sensitivity to gluten, are also sensitive to dairy.
This part of the elimination would take the longest, due to the long-lasting effects of gluten in the body, well after total elimination!
Continue the probiotics, or even better for the long-term, look into prebiotics and optimizing your diet to include foods which increase naturally your healthy bacterial flora.
Avoid like the plague any foods which do not add good nutritional value, reduce stress and anxiety where possible and look into additional ways of strengthening your immune system.
If not sure how to go about it, please post again.
There are many knowledgeable members here, who can offer some suggestions .
Hello~I hope that by now you are feeling lots better. If you are still having some issues, I would certainly see a gastroenterologist for some tests.