What Causes Pressure In The Head And Post Nasal Drip?

Hello, I have been not well in my sinuses and head for about 3 months now. I feel pressure on the top of my head, pressure in my sinuses, sinus drainage down my throat, nausea and a raw feeling in my nose. I also have hot sweaty flashes, and it is not hormonal. I have been through augmentine antibiotics, prednisone 40mg for 5 days, non of it helped. I have seen a ENT who said he feels it is neurological. He also did a CT scan of my sinuses which is normal. I have seen a neurologist who did blood work which is all normal, and I am scheduled to have an MRI on Monday. They have all told me it not allergies or a sinus infection. The neurologist said it might be something called, New persistant every day headaches which he would treat me with a migrain medication. What do you think of all of this? Frustrated Jeanine