Hi, yesterday, while at work, I suddenly felt a very sharp pain on my right shoulder . Usually I would have disregarded something like this, but it was very similiar to an experience I had about 6 months ago: I was at a picnic, on a very hot day, and suddenly the same sharp pain arose (exact same area) and I blacked out for approx. one or two seconds, since it happened in a flash, I didn t fall to the ground although I almost did. At that time I assumed it was a mini- stroke , but I went to see my doctor and after bloodwork among other tests, he found nothing. As for yesterday, I did not notice if I slightly blacked out but it is a possibilty because like last time it happened so fast it could have went unnoticed. Some background information about myself: I am in my mid 20s, physically fit and have no health complications that I am currently aware of. So any ideas what may be the cause?