Your doctor has prescribed antibiotics and i am sure he must have also given paracetamol
syrup if there is fever
. He may be needing probiotics.
But without associated crying, heavy fever is normal during this age bcoz your child's stomach is getting adapted to other foods.
If you have changed the child from exclusive breast milk to other feeding, this may happen and nothing to worry.
You can give breast milk.
Mashed dal rice, banana, mashed potato can be given
Bottled milk can be given , but make sure you have sterilized the bottles or get some new ones at frequent intervals.
you can also give commercially available formula foods.
Hope i cleared your doubts.