I'm an older guy 57 with similar symptoms, ache on the right side of my head. Went thru 10 years of misdiagnosis, pain getting worse the whole time till it got to the point of affecting my emotional health, I kinda lost the ability to control emotions. Lucky, an insurance switch happened and a new doc went right to ON diagnosis. Had a nerve block done and pain was (mostly) relieved. Over the past 4 years I've had two surgeries by Dr. Ducic at Georgetown Med center removing nerves in my skull. It helped a lot...maybe 80%...but still dealing with some daily pain.

Headaches can be caused by many things, but if limited to one side with the dull ache daily ON is a reasonable guess. So go get a nerve block done and also demand proper pain treatment...chronic pain will screw you good up if left untreated.