Experiencing transient head pain behind both ears upwards especially when moving head positions. What's happening?

A neck problem. Pain in the area that you described is from irritation of the attachment site of muscles that support the neck. In someone 49 years old this usually represents osteoarthritis of the joints of the neck with secondary muscle spasm. Our bodies use muscle spasm as a protective mechanism for injury, inflammation or infection. Unfortunately muscle spasm also causes pain at the involved site.