Hi I am 13 and today I noticed I had brown discharge on my underwear I was dreaming out so I googled it and it came up with it might be your period I eventually told my mam   And the problem is that I am going on holiday in 1 day , and all I do on holiday is go in the pool and go to water parks. So I googled for another 10 minutes to find out more and someone said not to use a tampon as it could give you a shock and another said that it will only last for a week each month for 2-3 months  so any more info that could help .