Constant headaches needs to be investigated first. Single sided headaches could be migraines. It could be genetic.
There are triggers, usually food like chocolate, peanuts....if it is migraines there can also be issues with vomiting when u have h/a and light exposure is hard.
Also there could be single sided headaches called cervicogenic headaches from cervical spine.In these neck ranges are affected....
Next Steps
every headache could have some level of neck dysfunction. this could be helped with mobilization and self mobilization.
Health Tips
visit a physiotherapist after a scan first