I would take him to the vet. It sounds like it happens way to often. The last time Kaji presented the same symptoms, his tummy was so upset and in so much pain, Kaji actually lost the ability to control his bladder.
He would pee in his sleep and not know it.
His upset tummy was caused by nerves. (he's a very shy, nervous boy) I had left him in good hands for 1 evening out with my family, but Kaji didn't agree.