Why oh why do i take these panic attacks?

Okay so I had to go to thanksgiving meal on Friday night because my boyfriends family were home from America. So we went to Baltray golf course for the meal which was really nice, but I began to feel really weak and my head started spinning, so I went outside for a little while and that made me feel a bit better. Then i had to go to work on Saturday, it was reeeeaaalllly busy because there was a Charity event on to raise money for orphans in the Philippines. The room was really warm and I started to feel sick, I was serving a man a pint of Guinness (which I must admit looked fairly good!) but then my eyes began filling up with tears and my breathing started going, I had to run out the back and one of the girls I work with Sinead helped me and reminded me I have to breath and stuff. Can anybody please tell me the reason for these things always happening to me? It's seriously starting to annoy me at this stage!!