When i lay on my back my head begins to hurt and i feel pressure?

Might be migraines.: There are many causes for migraines, from eating foods like chocolate to drinking wine to exposure to light to being upset to much more. These are often associated with dizziness, visual changes, and nausea. Your lying down might be a trigger for them. I would say first to try pain relievers that you normally use designed for migraines, and if they don't work, see your doctor for more work-up.