Something worth trying could be to check the salts that you use. Many processed salts are filtered to contain mostly sodium chloride (NaCl). The natural salts tend to be a bit more variation than that, and tend to include potassium. The balance of sodium and potassium may affect the blood pressure.

What you eat is one factor, but it's also how you lead your life. Take it easier and exercise, doesn't need to be running out of breath type stuff, walking and gardening will help.

Stiff upper back and back of the neck can increase the blood pressure (I definitely can feel when it happens to me), as they are a result of bad ergonomics and stress; likely both at the same time.

God bless