Hello, Worms sometimes cause painful tummy mostly. Other complaints are different. You consult your doctor or online consultation. Follow my Instagram/tiwari_child_clinic for Health Q&A. 🙏Tiwari Child Clinic Delhi🙏

You may give Deworming medecine The behaviour issues especially sleepiness are not related to worms Please do a thorough check up

You can give deworming once and see. But these behaviour and digestion problems are common at 20 months of age. He should be better in a few days. Give fresh home cooked food only. Avoid outside food especially those with maida like bread, bakery foods, biscuits. Give banana, apple daily. Does he look pale? Get a check up with pediatrician. He may need iron supplements.