Grey Bump on Dogs Neck

My 5 year old male lab/husky mix has this  bump on the back of his neck. I first noticed it a month or two ago but this past weekend I decided to check on it again and it has definitely grown in size. It also seems to hurt when I touch it, he doesn’t yelp or anything but after a few seconds he tries to move so I can’t bother it. It’s a little hard but it’s not rock solid, and I’d say the size of a BB gun pellet. Other than that, everything is completely normal. Any ideas of what it could be or if I need to get him to the vet asap?

Hello!  Im afraid that there are a few possibilities.  As well as a pimple or polyp, I wonder about a cyst or infection in the hair follicle, or something demodex-mite related (sometimes I think they get an inflammatory reaction around them); an ingrowing clump of hair; I can't rule out things like the start of an autoimmune reacton or even a cancer, although that's nowhere near the top of my list.  I suspect that some of these will resolve spontaneously, some will burst and out will come a tooth-paste like cylinder of inflammatory goo then either resolve or continue, and some might get worse and irritate the patient or - if cancer were to be involved - simply grow.  I'm not sure how long it's been there, but would not wait and see for too long before a chat with your vet to establish a strategy for dealing with it.

Thank you so much! He’s seeing the vet today thankfully but you’ve helped my anxiety ease up a little until then! I truly appreciate you taking time out of your day to respond.