Running down my legs?

I started having sex with my boyfriend, this is my second person I'm having sex with. His penis is larger. But some how when I have sex with him after I'll get a burning sensation, I'm not sure if he doesn't shower properly or what is it. Also this morning I woke up and clear white water was running down my leg. As if I had an orgasm but the last time we had sex was yesterday.. So what can the substance be ??