Hi I Was Just Wondering, I Have An Irritation On

Hi I was just wondering, I have an irritation on my lower area that came up about 3 months or so ago, after I started using lubericant during sex, but it hasn't Gone away, and after intercorse last night, I found that it is sore and had a bit of pus around it, but there are also more then one, I think there is three. Is this an STI? Or just an irritation to the lubericant? Because it hasn't gone away at all it just forms a kinda white crust over it and then comes back.