What STD Do I Have?

I've had skin problems for the past month. My mother has eczema, so I didn't think much of it. I had what appeared to be an eczema rash, and my skin was very dry and flaking in some places. Then 2 weeks ago, I started getting sores. They weren't that troublesome at first, and I thought they were caused by me scratching excessively when I had ezcema. But then they started showing up in places where I didn't have a rash, such as my SCALP and the back of my neck.

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Around that same time my chin area and some patches in my hair started getting "scabby". And they aren't razor bumps or anything like that. It's like piled up layers of dandruff and crusty skin, and if I try to peel it off, it hurts and there's a yellow pus to it.

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And then 2 days ago I woke up and found a large lump in my scrotum. It was small at first, but in the past few days it has grown to be larger than my testicles, and now it hurts a bit

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I plan on going to get a some STD tests next week, but I would like to know if anyone has any ideas on what this could be. Thank you.