I gave my daughter sudafed D and she is still congested can I give her Mucinex?

You should first figure out why she is congested. And how old is she & does she have a fever, is she eating & drinking normally? If she doesn't have a fever, I would try an antihistimine like Zyrtec first, children as young as 2 can safely take it. If she has a fever of more than 101 may be a bacterial infection that would need antibiotics. If no fever than the Zyrtec, saline drops in the nose, and humidifier (cold air) would probably work best!! Hope she feels better!!