Hi there,
sorry to hear she's feeling so poorly. You haven't been very detailed about her symptoms, so just to be sure, id she had diverticulitis she would be suffering:-
Lower abdominal pain (usually the lower left).
Nausea or being sick
Sharp cramps in the tummy
Constipation and trapped wind, OR diahorrea.
Feeling feverish and flu-like symptoms.
It is usually caused by an infection in the part of the colon called the diverticulum. This can happen when weak parts of the bowel bulge out and a bit of food or pooh basically then gets stuck and doesn't move along in the bowels as it should.
If your mum does have diverticulitis, you need to look at giving her something known as a 'Low Residue' Diet. This will give her bowels an opportunity to rest and heal.
You can google the term low residue diet and get lots of information on meal preparation. It basically involves cutting back on fibre until she has had chance to heal. Here is another useful diet link
http://www.diverticulitis.org.uk/diverticuliti s-diet.php
I would also recommend she be given a course of broad spectrum antibiotics to illiminate any infection lingering around in the bowel. Her GP can prescribe these.
You might need to push the GP and hospital to get a referal to a specialist to investigate this further. Just to ensure that you are definitely dealing with diverticulitis and not something else like Colitis.
Best of luck!