Hello and welcome to the forum. Very sorry you are having this issue. The first thing to do is to see your doctor. They can examine you and guide you best. Have you ever suffered migraines before? Has there been any reason to suspect a muscle strain or injury on that side? Very tight muscles there can cause pain. One health issue that can cause left sided head pain is occipital neuralgia. https://www.webmd.com/migraines-headaches/occipital-neuralgia-symptoms-causes-treatments#1
This is when the nerves that run from the spine up through the scalp become injured or inflamed. This very often happens from tight muscles which causes pressure on the nerves. This is not serious but uncomfortable. Things to try after you talk to your doctor include a heat pack on your neck, a massage of the area, gentle stretching, an alternating ice pack to the area, Nsaids such as ibuprofen or Tylenol. If these things don't help, your doctor can take further steps and prescribe things that might.
Let us know how you are doing.
That's a long time to have a headache. Does anything help? Do you think it is tension and stress related since it's not there when you are sleeping? I mean, I guess you wouldn't have a headache while sleeping but headaches that are bad wake me up. And you mention some panicky feelings. This might be an area to think about if it will help.
I'm a fellow headache sufferer so understand.
Have you ever seen a doctor about this? I think you should.
It could be something in your house, or work, that is causing this, like mold, or an allergy to something like plants, candles, etc. It could also be something more serious, but you really should get this checked out.
Are you on any medications that list headache as a side effect?
Headaches suck. I hope you find the cause. :(