It would be a good idea to see a medical provider and get a complete HIV and STI checkup. If its been < 72 hours since the sexual encounter, you should seek care right away as PEP can prevent HIV if started soon after a possible exposure to HIV. If its been more than 72 hours, its still a good idea to talk to a medical provider. You can get tested for HIV and STIs, and talk to your provider about whether PrEP is right for you.