If it is as bad as it sounds at its worse, I would get him an appointment with the pediatrician in case you need a referral, as soon as possible. If he had it before and it has worsened it could be a tic, obsessive compulsive behavior, or related to anxiety . If it came on all of sudden it could be possibly related to a recent strep infection, PANDAS. (Which is still being researched.) I am familiar with sensory processing disorder, but the behaviors described sound more involved.
Have you asked why he is making the repetitions and spitting? For example, is he holding saliva because he doesn't want to swallow? He can't help it? He might be able to tell you why he does it. Etcetera.
My PG kid's issues, different than your child's, started at 4/5. It has been an ongoing process finding help. It seems we go about 4 months of a year resolving something and a new thing pops up within one year. It might be helpful to have a pediatrician and a regular psychologist for when issues like this pop up. Trusting their professional judgment to make a referral is important.
I hope it resolves soon.
