Centimetre type size sore just appeared on foot.

[condor]

Yesterday, I noticed a centimetre type sore had just appeared( seemingly out of thin air) at the base of my front toe ( front of foot). It wasn't there the day before, and there's been no pressure on the foot, so is an instant appearance.

I have a rodent ulcer on my face,neck and arm, and am currently waiting for a dermatoligist consultation ( been 6 months since I got those, but consultation in a few weeks time). If these rodent ulcers were that important I'd have been seen a lot earlier - do I need to bother my GP about another one? or just wait till I see the dermatoligist?

Or, is it something else?