Why do I feel a headache on top of my head. Anxiety? Brain tumor? Sleeping too much?

I've had a major panic attack 2 years ago and I suffer from mild anxiety attacks sometimes.
I've been working about 32 hours every week and don't think that's enough to get a stress headache, -I may be wrong. Today I slept pretty good, slept from 2:30 am to around 11 am. When I woke up I was watching videos on my iphone and watching tv. At about 3:30 pm I took a nap and woke up at about 5pm with a major headache-Its 9 pm and still hurts a bit. I worked out Friday on my trapezious muscles and my shoulders as well. I've seen a lot of websites that say it might be tension headache or stress. Other's say it can be a brain tumor (creeps me out:/ ). The area that I feel the pain is ontop of my head. At the very center on top of the skull. I don't know what caused it but if you may please help me out, it will calm me down a bit from my anxiety and it'll really help me. When I get headaches at work, they' usually feel like stress headaches. I didn't eat lunch only potatoes at around 12 and wasn't hungry until now. A very tiny bit of nausea too. My neck feels somewhat stiff as well.

Chances are, you associate the panic episode with the freeway and you begin to think: If it happens on the highway, it could happen elsewhere. As you become more and more concerned about recurring panic attacks, your symptoms occur more frequently and you avoid more and more places until your world becomes very small. Eventually, you may come to believe that the only safe place is within your own home. The nightmare has just begun. Helplessly caught up in a panic-avoidance cycle, you are now dealing with the phenomenon known as agoraphobia.

This book discusses five of the anxiety disorders recognized by the American Psychological Association: panic disorder with agoraphobia, panic disorder without agoraphobia, social phobia, simple phobia, and generalized anxiety disorder. Each of these is seen as a rather distinct problem, and each can be recognized by a set of more or less predictable characteristics.

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