My 3 yr old has had a runny nose on and off for about 3 months now she did have an ear infection but was treated with antibiotic. what do i do now?

Not sure what asking: 3 yr olds often have viral infections, or may be manifesting allergy symptoms. Are they having fevers or other symptoms of infection? It might be helpful to sit down and have a lengthy chat with your family doc or pediatrician about what you can expect in your child after they have examined them. There are also a slew of books in lay language on child-raising which may help. Hope better soon.

Sinusitis: With persistent nasal draiange.. I would consider having her evaluated for possible sinusitis (chronic) or adenoiditis. Start wtih your pediatrician, but being seen by an ENT is not a bad idea.