I had sex last night without a condom and now I have mucus coming out my vagina. Not sure what that can mean?? PLEASE HELP!

I was doing laundry, and my girlfriend's panties were inside out and had a large, slightly yellowish, crusty stain on the crotch. We have not been having sex lately. I know that girls often get stains there from mucus and what not, but because this was crusty. I am alarmed that it might be semen backflow from another man. Are girls' mucus stains ever crusty? If there is semen there, should it smell like it even though it is dried? Please tell me anything you know.

I always get a sticky white goo in my pants, when I wipe it off it sometimes looks abit yellow. It doesnt itch, smell or I dont suffer from any pain with it. What do you think it is, and who do you think i should see about it?

I'm 16, ive been dating this guy for almost 7 months and we're sexually active. I'm pretty educated about sex I would say, but no one knows everything so here it goes.

1.) Sooo, we tried anal sex, and about 5 hours after this occured I had "anal seepage" mucus, with some spotting of blood. I'm guessing this is normal, very icky but normal, but what a wanted to know is will this keep occurring? Because I'm not so sure I want to continue doing this form of sex if this is going to continue.

2.) We have a curfew so sometimes, when we want to do something, and I casually mention we don't have time, he will say "it's ok I'll force it" mainly when I perform oral sex, my question is, how is this possible? When you ejaculate its natural, I mean I know you can hold it in to prolong your sexual excperience, but forcing it? I'M SO CONFUSED PLEASE HELP!!! SERIOUSLY!