Unknown wound

could anyone advise what this is, it started of as like a blood blister, I have been cleaning with Leucillin spray but he keeps scratching it and it's not healing. I have a vet appointment next week but is there anything I can do untill then, thank you.

Hello - next week is a long way away and if the scratching continues, this might look very different by then.  It may be worth a chat to your emergency vets in order to see what they suggest.

It's easy for me to say 'do something to stop the dog scratching,' but the trouble is that a bad itch with no way to scratch it can be extremely uncomfortable abd may get worse, so your vet might be able to offer something to reduce that.

I did wonder about Lyme disease - in my experience, this doesnt usually itch but if you are in a Lyme disease area, that may be something that your vet is looking out for and ought to be considered at least- another reason for early presentation.