It doesn't look like orf to me, and if there is only this one spot and only on this one sheep then it's unlikely to be orf. However, even if it were orf, you can do nothing about the underlying viral infection but can treat any secondary bacterial infection especially if, as in this case, it is worsening.
If you think it might be orf, then washing the face in a solution of Daz (and yes, it has to be Daz, not Bold, Ariel nor any of the other brands) does seem to help. I'd still do the salty wash on this spot first, and use antibiotic or antiseptic spray after, though.
Good luck - let us know how you get on!