I'd suggest that you stop trying to self diagnose from the internet, and get proper medical attention to find the problem.
There is a tendency to find much more serious illnesses than we really have, and there are lots of other factors that need to be considered.
I don't understand why you consider pain meds are not needed for "just a stress headache."
A headache is a headache and if it stops you from functioning then it needs to be addressed, initially by pain meds.
A stress headache is an easy one to treat, by reducing stress levels and a change in your responses to stress, over time.
Rebound headaches can occur, but you would need to repeat the process a few times to see if it is a constant.
It can take a while to determine the best pain killer and dosage for a patient, so give the doctor a chance.
Keep a record of the headaches, what you have been doing in the days before, and so on. This may give you a pattern.
Sometimes the pain occurs a day or so after the activity.
Stress can cause all sorts of muscles tension problems, and the worst headaches.
I had that for many years. If that is the cause, try muscle relaxants, hot baths, massage, better sleep, less computer time etc.