Think I have and STD. Had a infection!

Hello, so last year I had sex with my ex girlfriend and about 2 weeks after I started itching my penile shaft and my testicles itched badly but I didn't pay it any attention because I ad recently shaved in that week, however I had sex with another girl she didn't have any complains about itching or anything and my itching had stopped in the end of the week however months had past about 5-7 months n I have a new girlfriend the one I'm currently with and we had sex a month ago and about a week after she told me that her vagina is itching her badly so she went to the doctor and they said she had a bad infection so I was wondering if that I have an STD, but in that time when me and my current girlfriend had sex I had just came back from camp and I didn't have access all the time to water so I didn't get to bathe myself thoroughly so I'm wondering if its because of that why she had a infection