Hi and wlecomet to HCM.
This can be gonnorhea again or any other bacterial STD
. YOu should do swab test again and verify the exact cause and then treat yourself and your girlfirend as well. There is no other option. I suggest to use protection even after treatment. Sometimes infection isnt healed completely and then it oftenly relapses. YOur girlfriend should do ultarsounds of pelvis as well to see is there any deep infection. Wish you good health.