Girly question... please answer if your a girl! .?

I'm 13 years old.. haven't started my period yet.. well.. I think I have.. ok sooo.. I worked out this morning and after I got done I went to the bathroom and looked in my little pad thing and saw brown slime... ewww. It's not crap I can promise you that.. Yes I know.. kinda personal right.. but I don't wanna go tell my mom yet.. embarring.. so I'm asking total strangers for help instead :) I had the same thing happen to me about 4 months ago and thought I started my period but it only lasted for 1 day.. I'm desperate for answers.. is this normal in the beginning of starting ur period?? What is wrong with me? :'(