A.S.
Have you ever asked the doctor about a vocal A./or motor tic? You may want to google both A. read up on them.
This may sounds NUTS - my son had a what seemed like a minor vocal tic that appeared to go away once removed foods he is sensitive to (A. he had ALOT of them).
Now, according to my ped they can come A. go on their own. I don't totally buy that . . .
Good luck to you both!
PS: I found it best to not call much attention to a vocal tic - if you do it becomes almost irresistable to the child to do it (kind of like if someone tells you to not clear your throat).