Sex with people from a different country

This has happened to me twice and I don't know what to do with it. When I had sex with someone from a different country. First one was from mexico and the second was from DR my vagina swells and gets super irritated. I used a condom both times so but I don't know what it is. It gets super enflamed and last time the pain and discharge and swelling lasted for a month. I just recently had sex with the second one and wondering what it is. Last time I went to the doctor after a month and they said all test results came back fine but there wasn't as much swelling because it went down and stuff... HELP