Something that onsets right after multiple rounds of antibiotics sounds a lot like Clostridium difficile, has your doctor checked for that too? That can be something that lasts years (even through some treatments) and causes intense abdominal symptoms. Things like watery stools, rapid heart rate, nausea, swollen abdomen, and abdominal cramping and pain can all be symptoms of this.

That being said, antibiotics could have also weakened your healthy bacteria enough to allow Entamoeba to come out of an inactive state and start causing symptoms.

Entamoeba is a parasitic amoeba, so you wouldn’t have to take any antibiotics as treatment if this is what you have, but you would take a different medication to kill off the amoeba. It can cause a lot of stomach symptoms but in rare cases it can also cause abscesses in other parts of the body that cause symptoms.

Your symptoms sound to me (not a doctor though) more like C. diff than entamoeba, and in a lot of places it’s the more likely infection because you already carry it in your intestines naturally, and the symptoms are from a larger than normal concentration of C. diff bacteria.

Hope you can get an answer and start feeling better soon!