My 11 year daughter who is high functioning autistic has gained 12 pounds in the last 10 days.  Her belly is extremely extended (bloated) but she doesnt complain of it hurting.  I had to find pants 2 sizes larger than she usually wears in order to go to school.  She is at the 5th percentile for height and 10th perrcentile for weight before this started.  Could it be from starting the medicine Intunive and or buspar, which she takes for extreme anxiety and ADHD?  She hasnt been eating any more than usual.  She has a terrible diet, always has, but will not eat anything else.
Intensive may cause constipation but such abdominal distension with significant weight gain in short time seems unlikely to be due to constipation. Such abdominal distension may be caused due ascites or intestinal obstruction. Exact diagnosis can be made with USG Abdomen. Consult your doctor and ask for this investigation. For further queries regarding this disease or its medications you may take my appointment at Chat Doctor.