Hi Coreyn, sorry you are going through this.  Yes, I had the same thing as you with this cycle.  It was a constant pressure on the right side of my head.  The worst was that my neck was in alot of pain too.  I used a lot of BenGay on my neck which seemed to help a little.  I had to sleep on my right side because if I flipped over or slept on my back, I would get a headache within a half hour.  How long have you been on the D3?  My headaches went away within a few days of being on the regimen.  As for the pressure, I'm still getting a much milder version off and on but I think that it's the cycle telling me that it's not over yet.  I don't have to sleep on my right side anymore either.  Once I started the D3, my headaches went away.