It is difficult to diagnose conditions over the internet as I would need to see it, take a medical and sexual history and do some tests. What I can do is give you some general information based on what you have written.
It’s common for us to see people with molluscum at the clinic as they pass from skin to skin contact; they usually go away after one treatment. It is also common for us to see people with fungal rashes as well, common to get these in the groin area.
It is difficult to say what could be causing the tingling between the legs. STI like chlamydia are common and most of the time they do not cause any symptoms or can cause mild symptoms like itching in the urethra (pee tube).
As you are concerned about a possible STI I would recommend asking your health professional to do a STI test and exam for you. If you are uncomfortable asking them for a test you could always come to the STI clinic.
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