I have always been a generally anxious person, but in the last month I've been experiencing symptoms I'm not sure add up. The anxiety (or whatever it is) seems to hit me in my head, where I begin to feel confused and less alert, with a tightness in the back of neck and contractions/jolts in the head, a feeling of doom/terror, and then the racing heartbeat kicks in afterwards. I never have the heart attack feeling that others report- it's all located in the head. 

I've had two episodes the last month where I thought I was about to have a seizure or stroke out. Called an ambulance both occasions, they come over, do their tests and turns out I'm fine. It is so difficult to explain the weird, confused feeling in my head. It's not pain, it's something else. I wake up at 5am and it's there and the terror kicks in.

Does this sound familiar to anyone? What the hell is happening to me? I am on a waiting list got MRI scan to at least rule out anything physical. I'm very worried either way, as I cannot live like this.