Is it stomachache like flatulence, indigestion or food poisoning? If this is felt in the lower abdomen, this may be cramps as the uterus is expanding and is normal. Flatulence and indigestion is sadly normal as well, perhaps can try to get more fluids and fibre in the diet, and avoid gassy foods. If food poisoning and diarrhoea best to see a doctor.
So nice of you to be such a caring dad. Been cramping all the way on and off till now halfway thru preg so I suppose it’s normal stomachache maybe she wanna watch her diet try to eat more greens and drink water. Helped me with my constipation