Hi and welcome to the Migraines & Headaches Community.
Stress most definitely causes migraines and tension headaches and whole list of medical issues. Just because you don't feel it emotionally does not mean it's not taking it's toll on your body. You need to do what you can to lower your stress level. If you need to ask your doctor for something...Xanax, Ativan, etc....do so. In the meantime here is a few over-the-counter tips you can try for headaches....
1. There are several symptoms of migraines and what causes the pain of a migraine is the blood vessels in your brain become dilated. So, sometimes it helps it you put a bit of pressure on your head. I am sure you have already been doing this unconsciously with your hands from time to time. So, get a bandanna or a cloth headband and wrap it snugly around your head.
2. If you rub Mentholatum across your forehead and on your temples that helps relax those tense muscles. You can do this with or without the wrap, depending on if you like the heat or not.
3. Try either a cold or hot pack, whichever is more comfy to you.
4. The best OTC meds that I have found that works is Excedrin. It is a combo of Aspirin, Tylenol and Caffeine and that happens to be an excellent combo for migraines.
5. I mentioned caffeine before...well, drink coffee, Mt Dew, take Vivirin...sometimes a mega dose of caffeine will stop it in its tracks.
6. If you get nauseous or dizzy get some Meclizine from the pharmacy (the stuff behind the counter) you can take 25mg three times a day as needed. Yes it works on both.
Your story doesn't sound strange at all. If you don't have any other symptoms it really sounds like migraine. But I wouldn't call it a stress headache. Sure migraine can be triggered by stress but it can also be triggered by a number of other things and sometimes it just comes on anyway. So to call it a stress headache would be to oversimplify it a lot. It is a complex illness.
Are you sure you don't have sinusitis? That is rarer but can sometimes cause similar problems as migraine.