It is possible for some .... gluten intolerance would be the most likely culprit.
If allergic you should see improvements with using antihistamines like Benadryl, and H2 antagonists like Zantac.
Allergic reactions often have redness, tingling, and heat.
The only way to test this accurately is to go on an elimination diet.
The swelling in your abdomen, may be the fluid swelling up in the intestines. This messes up motility and results in gas because of the bacterial overgrowth that may occur. Absorption of nutrients may be affected because the intestinal walls are so swollen up food cannot pass thru the lining.
GI symptoms are often the first sign of HAE.
And not everyone gets the same symptoms, and this complicates diagnosis.
Some foods release histamine, but you can block that with antihistamines and H2 antagonists. You can see an allergist, who BTW will also possibly be certified to evaluate for HAE.
Epstein Barr is implicated in causing lymphoma. However, most likely if you had this, your arm(s) would be swollen too. Lymphoma can cause backup of fluid in the lymph system. This can occur in the abdomen or elsewhere. The fact that yours is only in the hands, doesn't suggest this.
You can try wearing the wrist splints for carpal tunnel anyway.
These keep the wrist in a position so that fluids can enter and leave the hands, properly and not build up. The carpal tunnel is very tight in some people. There are also compression gloves, made for those with arthritis:
Lastly there is TOS--thoracic outlet syndrome.
Here is our forum on that: