Welcome to .ehealth!
I'm sorry you've had such a hard time getting rid of this headache.
What you are describing does sound like a tension headache. So, you should try not to worry. They are not serious. (though they can be painful).
You said that you are on painkillers. What painkillers are you on? They have prescriptions for tension headaches. I think you might want to call you doctor and ask if it would be an option for you. (the brand I take is phrenilin forte)
You should definitely continue the stretches. They might not feel as though they are giving you immediate relief, but they will really help in the long run.
You may also want to ask your doctor about a tens unit. They can be very helpful as well.
The only other things to make sure you are doing is pretty basic. Make sure you are eating properly. Take a multivitamin (this will help from getting muscle cramps) especially potassium. Make sure you are drinking enough water. Dehydration can cause muscle cramps as well. Lastly, make sure you are getting enough sleep.
I hope you are feeling better soon. Keep us posted.
.p.s. Good luck on your exams!