At 5 to 6 months u can start compliments feeds, which will be mainly simple food, no complex/combination foods It may include some fruits (some need boiling/steaming like apple), and plain dal/rice or dal+rice but without too much salt or sugar and no masala/spices Start a new item every 2 weeks, not all at once, so that baby can adapt to the new taste

Yes you can start with complimentary feeds which are semi solid.

Consult with Pediatrician physically for further evaluation and treatment