I am very sorry to hear that,and hope that you can get better soon.Sometimes there is nothing serious but we frihgten ourselves.I think everyone can have nightmares.That means nothing.I think there may be something unhappy in your daily life,or you are worried about something,so you have nightmares.Well,do something you like,and relax yourself.Make frequent talking with your friends.The most important thing is to fulfill yourself.
Best wishes !