Oh wait @Ford ,
I wasn’t paying attention; you are using a Multires Modifier.
Then that Edit Mode Smoothing won’t work. You could go back a few Sculpt Levels in the Modifier until the problem area looks okay and then slowly go up again, Smoothing each Level.
Or just start over and Delete Higher Levels.
Mesh Modeling mistakes are often fixable, but with Sculpting, it is usually easier to start over. Get into the habit to Save Incrementally often, especially when Sculpting, so you have ‘recovery points’ and you don’t have to start from scratch each time.
