Lymphadenopathy of mesenteric lymph node? Happened to me after a month long stomach bacteria I assume may have been Helicobacter pylori, which is more common than people know. I could not eat for a month. It is associated with development of abdominal problems. Probiotics? Cut out dairy?
Hernia might match this symptom. Does the pain increase during straining of any kind?
You can look up medications on the internet and read about adverse reactions, and side effects.
Some diabetes drugs can cause gastric problems, so if they subside after you have stopped taking them, it likely is related to the medication.
Oh also, you may want to get a test for food allergies and see an internal medicine doctor (I am not a doctor)
I had this and was diagnosed with a genetic disorder called Familial Mediterranean Fever. If you are a women, it could be something related to ovaries like cysts?