Pimples around neck

Hi everyone,
I have noticed lately that my cat scratches himself so badly and i noticed there are insects in his fur so i asked a vet and he gave me drops to use on the back of his neck. Now after a week i notice that there are pimple around his neck. Am so upset and sad about it. Do u have any isea what those could be and how to treat them? My vet is away for the next two weeks and i need help please.

Thanx in advance

Is he still scratching that area, or not?  From the picture, it almost looks like a small scab, rather than a pimple.  But if he's not scratching anymore, could it be a scab, as if it was a wound that's healing?  Sorry, I really can't tell from the picture