What is this please?

[Lastofyou]

Behind my ear at base started to feel very tender yesterday. This afternoon I had a feel and realised there is a large lump/swelling behind it. It is really sore. I've attached a picture but what is it please? Wondering if I should lance it with a sterilised needle?

Leave it. It will go away on its own.
Don't break the skin.

I am in no way a medical professional, but given where it is it could be mastoiditis, which can be very serious.

When I had a bad ear infection they were very careful to check behind the ear, just in case.

I would phone 111.

What a ridiculous thing to say. You have no idea what it is!

Thanks. Will try and resist the urge to stick something in it!

I had a cyst behind my ear that looked like that. Eventually had it removed on NHS three little stitched. They wouldn't at first as cosmetic but I was working in a call centre and the pressure from the headset kept bursting it. I haven't had once since I stopped smoking ten years ago.

I had something similar many years ago. I ended up in A&E and getting it drained. I’d see the GP.