S.H.
I had that once.
And yes, that "lump" was there for weeks.
I finally went to the Doctor to check it.
It was an infection.
It was what is called "Cellulitis."
I had to take an oral antibiotic. And THEN, it went away.
It was not going away on its own.
Mine was on my elbow too.
And there was no break in the skin of any kind.
You need to go to the Doctor.
And most of all, do not squeeze it or try to "pop" it.
That is what the Doc told me.
When I had that, it looked and felt just like how you describe yours.
I am not a Doc, but so you should go to the Doctor.
If you look up "what is Cellulitis," it will make you want to go to the Doctor to check your elbow.