5p sized welt, lump or bite

Hi, my 4 year old corjack (corgi russle mix) seems to have a welt like lump on his chest towards his armpit. It seems to be bothering him somewhat, he tries to lick it but can’t really access it. Because of the location and his hatred to anyone touching his legs i can’t get a clear photo.

It kind of looks like a tick bite, but i am guessing.

I can’t say his behaviour has changed much, maybe slightly more lethargic than usual, but still barks the house down at the slightest noise so I’m guessing he can’t be too bad.

Before i go calling the vets, i’m just after some advice. I appreciate I haven’t given much information to go off, but i don’t have much else to offer.