Lactulose is a stool-softener, so do you think her hard swollen belly is a result of constipation? Have you seen her do a bowel movement?
I can't imagine Lactulose being a remedy for over-eating...? Not unless it somehow caused constipation with hard stools.
A swollen belly, especially if she doesn't feel well, could be a few different things. Unless you know for SURE she's constipated. And even then, administer laxatives only after consulting the vet.
A good idea might be to get her to the vet. A swollen belly with obvious pain could be something serious, and needs checking out a.s.a.p.
That wont do any harm but you must feed little and often NEVER one big meal.When adult I feed twice a day never have any probs.....
If she does not improve you must your Vet for advice as soon as possible.