Its funny because at the time this happened to me I was pretty sure I was the only one on the planet who had ever experienced this!
That was 20 years ago.
It was at the start of my Panic and Anxiety Disorder, and I still remember it with such clarity!
I recommend you go to the doctor and get a full check up -- heart, lungs, throat, mammogram, etc. Really get checked out. Talk to your doctor and let him/her know you have some issues with panic and anxiety.
Ask him/her to work with you through this. Get recommendations for a therapist. Talk about meds.
Then seek out some support for the onset of Panic and Anxiety disorder.
These are some that worked for me:
1. Nutrition - change the way you eat. Severely limit sugar, caffeine and high fat food.
2. Exercise - get some. Every day!
3. Sleep - get some. Every day!
4. Massage - find a massage therapist who can work with you to relax your body, and help you get to know the muscles and structure of your body - so you are aware of what the various twinges and pains are REALLY about.
5. Meditation/Breathing - get a CD or DVD for yoga, meditation, or something else that can help you learn how to self-calm. It is vitally important to be practicing this when you're NOT panicking so that when the panic and fear set in you know what to do.
6. Creativity - find some creative outlet: writing, drawing, painting, dancing, knitting. It doesn't matter. But this activity can help you get distracted from focusing on "figuring out" what is wrong.
7. Therapy - I went to therapy to understand some of the underlying causes of my panic and anxiety. Fears that I picked up in Childhood and carried with me into Adulthood, false beliefs that I continued to believe in without question. It was very helpful.
Know that what you have is Panic and Anxiety. Your body is fine. Your imminent death is not real. Your mind is a very strong and delusional thing!