Thank you Sally
I really don't know what caused it. We didn't sleep with windows open, everything was the same. The only exception is that we switched covers because it is getting warm.
I haven't used the ice pack yet, but I'll use your tip when I do
My mom told me to apply vicks and cover my neck with a scarf for it to stay warm.
My boyfriend stayed home to help me (so sweet!), he helped me change my clothes (not even that I can do on my own) and made me breakfast and took care of the dogs.
I'll let you know how it goes.