DS is about the same age as your little one, he doesn't go to childcare but his sister does. He has had a cough bit of a snotty nose for almost 8 weeks, we have been to the doctors a couple of times in that period due to him ear pulling, he has had two ear infections but the docs haven't had an issue with anything else. So the antibiotics seem to do some good on the ears but nothing else. So I do believe things can last quite a long time, but I would go to the docs just to get her checked out - especially ears - but I think coughs colds at the moment are terrible and docs might not be able to do anything (Was told by doc coughs can last for months)