What is this on my thumb? A warr?

[Auntieobem]

Just as title asks - what is this? It hurts

It looks like a myxoid pseudocyst, if the redness is spreading & increasingly painful, contact your GP as you may need antibiotics dermnetnz.org/topics/digital-myxoid-pseudocyst

Thanks @Newhorizon21, I'll keep an eye on it

If I were you I'd soak it in hot salty water and hope it pops...

There's nothing tp pop.