Here are two muscles that are common with headaches, the temporalis and the superior oblique. This video shows how to massage these muscles to reduce tension and headache pain.
Sometimes headaches can be relieved by neck traction. Here is a video showing how to do this on someone you care about. Remember to go slow and get feedback.
Here is a step by step video on the left Epley maneuver.
Neutral spinal posture or a relaxed posture for your spine can be achieved in a zero gravity chair.
This video reviews the different tests to check for vertigo or BPPV. The most sensitive and currently best test is video oculography. A correct diagnosis of BPPV improves the success of treatment.
This video is about the process in picking the right pillow for you. For side sleeping remember to 'fill the holes' and keep the spine straight with enough support. If you have tried 2 or 3 pillows and your neck pain or headache pain continues then the problem is not your pillow but your neck.