My honest suggestions to you are:
1. Drink plenty of warm water
2. Use povidone iodine throat spray or gargles for a week or ten days, to reduce the inflammation and bad breath.
3. If you have any problems related to the acid reflux, it has to be treated with proton pump inhibitors.
4. Consult your dentist for a complete evaluation.
5. Avoid chilled food and beverages/smoking/coffee/alcohol if any.
Good morning lybrate-user
Yes you should start using brush as well as paste for your kids. This is the right time to cultivate brushing habbit in your kid.
There are good n number of kids brush and paste are available in market, all are equally good.
Brush at night with baking soda and rinse your mouth with lemon water, apply a slice of lemon into your teeth, chew few leaves of basil in the morning, chew neem leaves daily, visit your dentist for further.