My Daughter Had A Sickness Bug 3 Weeks Ago Since

My daughter had a sickness bug 3 weeks ago since then she hasn't been the same. Symptoms consist of headaches, occasional vomiting, very pale, black eyes, tired and the past few days she now has a very stiff neck and can hardly turn. Not sure if she has slept on it funny or it's part of whatever is making her poorly. Can I have some advise please as the soonest doctors appointment I can get is in 2 weeks time. Many thanks, Hannah.