Hi kittycatz
Last year, my Husband had the same type of telephone call from his Son, (my stepson)
It was his first holiday abroad and we were not too happy that his Mum had allowed him to go.
Anyway, in the middle of the holiday, he called to say he wanted to come home. He was in Turkey at the time. he wanted my Husband to fly out and bring him back which we refused to do.
We gave him the same advice you gave your Son. Two days later the panic was over. He was having a great time. WE are sure he had drank too much the evening previous to that and he had also had too much sun.
Naturally all his friends had been a bit more sensible and felt okay so they had gone out and left him. It was a case of "Feeling sorry for himself" My Husband was prepared to fly out to brin him home but youngsters nowadays tend to winge at the least thing. If he was old enough to go there in the first place as he so rightly told us, then he was old enough to come home without our assistance. We gave him 24 hours to see if he had changed his mind and thankfully, he had.
He wanted to stay after that.