Hi welcome to health care magic forum. It appears that the spot on your stomach is hurting only when you touch the spot. It means it must be a skin infection
. There must be an unerupted boil under the skin, or a gland. I advise you to consult a surgeon for diagnosis and treatment.
If untreated may lead to an abscess
and must be drained by a surgeon.
There is a possibility of gastric irritation also so it is wise to avoid the things irritant to the stomach like spices, chillies, junk foods, and oily food.
I also advise you to avoid potato, other tubers, pulses, and fish to avoid accumulation of pus.
Wishing for a quick recovery and thanks for calling.