I have gone through what you are experiencing and it stinks. I think the reason it all started was due to the fact you were so tired, and your body just sort of zoned out, then, being sort of scared anyway, your mind went into panic mode and being you were probably still tired, it stuck there. When we are tired, we will sometimes have things like anxiety/panic and these feelings will stay with us. I, too, have woken up with a start and worried if I will have the panic that day. For about 5 years, I could do nothing, was afraid to go out, cried all the time, had all kinds of fears, you name it. I went to many doctors only to be told I was in great health, it was in my head, geesh. I went to chirpractors and they adjusted my neck as the vertebrae in my neck that can cause anxiety were out, and these treatments helped more than anything I had done, I still get treated to this day. I have tried all the vitamins, minerals, herbs, etc, they work some, but, nothing to write home about.
You say you are going to Europe soon, well, the stress of as vacation can sometimes cause the panic, so just be aware that it can happen, also, starting school and moving will be a majour stress, so, try to take it easy during these times. Anytime I make a change, I go throught the panic, etc and have to tell myself all is well.
There are two books by Dr Claire Weekes that I feel would really help you. One is called "Hope and Help for your nerves" and the other is called "Peace from nervous suffering" I highly recommend them, I would not be without them. You can probably get them on-line through Borders or Amazon.
I would also add some B vitamins to your diet along with a good, food grade multi-vitamin/mineral complex. Also, try to avoid a lot of refined, white sugar and wheat and complex carbs.
I hope some of this helps you. As I said, I have been there, and I am here to tell you, it will get better. Oh yes, I forgot to add, I am a Christian, and pray has helped me a lot too, I must remember to lean on Him more though.