I’d leave the camp tbh, how old is your son? If you think he’s at the age where he can articulate himself well you should have a sit down and ask him how his thought processes go, does he feel anxiety from the stutter, what does he tell himself when he experiences a difficult speech interaction, does he constantly think about his past experiences regarding his speech, what are some of his triggers that cause him to stutter. Look into his eyes when he talks to see if he holds eye contact when he talks to you, examine his body language and see if he contracts any muscles, basically hyper analyze him and find the root causes for his issues, a therapist can do this too but I don’t think it’s that difficult, just listen