Well, those movement induced pains only happened once...
I read that if you bend over and it gets worse or if you cough and the headaches get worse it's a sign of a brain tumor. This doesn't happen to me, but if it did, is it 100% tumor or can it be something else, too?
The reason why the headaches get worse when bending over or coughing is because these actions increase the pressure inside your skull - and thus, increases the pain. However, even if you had an headache due to increased intracranial pressure, this still is most likely due to anxiety but none of us can diagnose you. Not only that, but there are less serious medical conditions other than brain tumours that can increase the pressure inside your skull.
Also, you should note that brain tumours exhibit themselves through other symptoms other than headaches and symptoms related to increased intracranial pressure. For example, depending on the location of the tumour in your brain, you will notice symptoms related to this location. These may be partial loss of vision, or hearing, seeing bright lights, flashes, stars etc. changes in personality, decreased mobility, speech problems, amnesia etc.
Also, having seizures is equally as common as having headaches and sometimes people will experience both.
Also, brain tumours will usually not effect your intelligence. They may effect your memory but they don't make you go dumb.
I experience headaches often and I often fear about it being a brain tumour. I am able to handle them a lot better though - anxiety wise. If it is only the headache I am experiencing, I usually can keep calm and reassure myself that it is anxiety or dehydration or something. Try not to jump straight to a brain tumour though when you experience headaches because you are probably going to get a lot more headaches in the future if you do.