Weird hot red spot on my back

I've been having left side low back pain for awhile... As well as leg pain/sciatic pain/shin/groin - all left sided.
Today has been quite a bit better, only mild low back pain and no other sx really. BUT.... (always a but) now I have a red hot spot - just to the left of my spine, it is hot to touch and really red - it's about 3" up and down and 1" across... Going along the side of my spine on low back. Where I have been feeling a great deal of the pain.

It's been there all day - the skin feels like a bad sunburn when I touch it.

Has anyone experienced anything like this? Any idea what could be causing it?

I am now noticing a bit more groin pain and my lymph nodes in my left groin are also swollen.

I do plan to go to the doctor (again...) but just wondered if anyone had thoughts on this.

Thanks.