WHOA- you were
forced to have sex with someone?
You should report this person/people...this is not something that should happen! You an go to the nearest hospital, and get a Rape Kit done where they check you for multiple things. In fact, if you do that...they will advise you on what to do with taking an ECP (emerg. contraceptive pill).
I have no idea of that's safe or not. In all honesty, I would call the nearest pharmacy. They will answer your question better than I'm sure most people here could.
Honey- I highly encourage you to speak out against this. You should never be forced into anything, especially something of a sexual and/or phyiscal nature. When you get the courage, you should get a Rape Kit done. They make sure you are clean, test you for viruses, look at bruising, and it's evidence that the police can you use if you want to press charges.
Good luck, and PM me if you need any more help. Things like this can be extremely stressful, especially if you have no one you can talk to.
:: hugs ::