Thanks for writing your query.
Weaning may sometimes result in indigestion
. Try to give light meals which includes foods in meshed form.
A negative stool sample indicates that there is no infection.
After reading your post, it seems that there might be a possibility that your child is having lactose intolerance
You can give curd or yoghurt as it may be beneficial.
If the problem persists, get your baby examined by a Paeditrician and discuss with your doctor for giving a probiotic
Also try to maintain adequate hydration of the baby by giving adequate amount of healthy fluids.
I hope this is helpful to you.