Hi!
If you had sex, there is a chance of pregnancy. If your friend is having bleeding that is irregular, and especially if it isn't her normal cycle, she should check a pregnancy test.
The best tests are the ones done at the doctor's office. So, I would suggest that your friend give her doctor a call.
If you don't want a baby at this point, regular birth control is the best (like pills or depo shot) but in the meantime don't forget about emergency contraception--Plan B--it is available at most major pharmacies without a prescription if she is over 18.
Good luck!
Dr B
If it was only two days ago, you have to wait at least 2 weeks before getting a correct result on a pregnancy test. Good luck!
It takes around a week for the sperm to get to the egg and another 6 days or so to implant and cause bleeding so it's doubtful that she is bleeding from a implanting pregancy just two days ago.
If you had unprotected sex there is a chance your girlfriend is pregnant. It's important to know what her normal cycle is because some spotting (Implantation bleeding) can happen when you have been impregnated. I'd say invest in a pregnancy test or you can go to a free clinic in your area that provides free pregnancy testing. There they can talk to you about what may or may not be going on. :)
Good luck.