Help with tampons!!!?

hi i'm 13 and i'm going on holiday in a weeks time, when my period is dew. So i bought some regular size tampons (so i can swim in the pool and sea) i thought i better try one. So i did i followed the instructions, but it didn't work i kept trying and i got agitated and my ears fizzed up and i felt really dizzy my vision went blury and i staggered to the floor my head was spining and my heart was pounding it took about 5 mins to sort of recover but i have a head ache and feel very weak i don't know what happend to me? and what shall i do for my holiday? HELP!!!