iiisecondcreep

Hello

For a few years I've been suffering from occasional chest pains.
The first time it happened I was 18 or 19 and I was in a shop and I had an extremely intense sharp pain in my chest, it only lasted a few seconds but I couldn't breathe and my legs gave way. I was on very strong antihistamines for an (unknown)skin condition at the time and I asked the doctor when I was in for a check up and he said
"whats probably happened is you've read the side effects of the pills and saw chest pains and imagined it"
I kid you not. I hadn't read the side effects but I did when I got home and chest pains was not a listed side effect. But I put it down to the fact that I'd been drinking which I REALLY shouldn't have been on those pills.
And that was it really until maybe over the last year. I've not been on the antihistamines since then and I don't drink(much) anymore. I started getting pains again, at first they were just twinges but over a few months they got worse and worse til the point that they were as bad as the first one I'd had except it kept happening and lasting up to a few minutes each time.
After a few weeks of the bad pains I went to the doctor who said it was probably muscular because of my job and sent me for chest x-rays.
I never got my results. The pains got less and less then went away. But I had one the other day, not as bad but still very uncomfortable, I think it was just a one off because it hasn't happened again.

I work in a job that involves a fair amount of manual labour but the first time it happened was years before I started my job and I never had it again til I'd been in my job for 2 years!
I've had my share of injuries at work, I did karate for about 6years and I've been horseriding for 15years so I've had my share of muscular injuries but it doesn't feel like any of those. the best description I could give of the way it feels would be like an extremely bad stitch in my chest and I can't breathe fully, if I try to take a deep breath it feels worse and I just can't!

Does anyone have any idea what could be causing this?
I'm 22, slim, I wouln't go so far as to say 'fit' but I'm certainly not unfit, I'm on my feet 40hours a week! And I'd say I'm pretty healthy, I hardly ever eat sweets or junk food. I am however quite nervous and a regular stressed eric(I'm finding more recently I'm getting short of breath when I get stressed but thats probably me just getting more unfit!) and sleep pretty badly. I sometimes get a fluttery feeling in my chest but i think thats quite common and to be honest, I think its quite pleasent
I grudge going to doctors because I don't appreciate being told I'm imagining things. (I've suffered from pains in my lower back for years, mainly if I eat or drink anything really sweet, makes me feel like I'm going to puke- was also told I was imagining that,they took urine sample and again-never got my results, so i just avoid anything I think will kick it off)

Anyway, be very interested to hear any suggestions, unless its 'your imagining it'!