After you get the sensation of cold on your neck and head what happens?
In a lot of cases these sensations are called auras.
Are you very stressed as this can cause what you are feeling right now. If you are very stressed go and see a physio and let them work on the muscles on your neck and shoulders.
I go to a chiropractor who massges my muscles in the shoulders and neck and then aligns my back. This has worked well for me.