What's the clear stuff in my underwear?

I have already started my period....I keep getting this clear goop in my underwear and its really annoying...I heard it might be discharge but i already had my period and it never goes away...I just started my period in May 2010 and it hasn't gone away since....Now in July 2010 more seems to come out...Im worried that i might have an infection or a disease or something...please help me!