DS's very sore and painful spot

[LetMeBe]

I noticed a red mark on DS's knee start of the week, questioned him as he's 4 years old as maybe knocked it at nursery. Typical 4year old didn't want to talk about it and I haven't checked it since.
Today whilst putting DD to sleep, DS was watching a movie and rather quiet so I went over to check and he said his knee was hurting he was tearful.
The pic is what his knee looks like now, very sore looking he won't let me go near it as he's scared it will hurt even more. He's in pain probably due to the soreness.
Anyone know what it could be? Best way to treat ?

I'd stick a hot flannel on it - as hot as he can bear, poor mite. That should pop it and I think that will help with the pain.

If he won't let you go near it at all draw around the red bit and see if it spreads. Its most likely an infection in a scratch but could be a spot. if its an infection and goes beyond the line take him to A&E or OOO immediately.

the hot flannel can be like the magic sponge in football if he likes the game?

Poor love it does look very sore. travail has given you some fab advice. Do keep a close eye on it and of it press get it looked at soon as skin infections worsen very quickly.

If he won't tolerate a hot towel, antiseptic and a plaster

Thank you, last night I did place hot flannel last night he was a lot calmer once warm heat was applied.
The whitehead came out even more, so with very little soft pressure it popped with blood and little white in middle.
Placed plaster over it and not as sore this morning as you can see in 2nd pic.

it might not be properly drained so will come to a head again. if he can bear it do the hot towel again and when it comes to a head, give it a good squeeze.

10/10 for excellent photos and update!!

That looks much better, I bet it was extremely satisfying! Hopefully it drained sufficiently to clear it, if not a repeat with the hot flannel will help.

Soreness had definitely reduced this morning and not in pain. He must have caught it during the day as it had slightly scabbed so hopefully on the mend. Still not sure how it appeared, just saw theses posts now so will use warm towel again if DS in discomfort again. Thank you for your great advice :)
it took a little struggle to take first few pics as DS was hysterical I'm sure he could be heard down the street!

It's a blocked hair follicle. Dd had one last year. Looked identical. Gp advised hot flannels and then gentle squeezing. D was fascinated as was I. Important to release the hair otherwise it will just refill.

What Babymamma said or leave it refill repeatedly and keep posting pictures