What Causes Nausea And Diarrhea Along With Twitching Sensation In The Arms?

My 12 year old son woke up last Tuesday with a severe stutter. I took him to the doctor that day. He had blood work done and an MRI. I was told the MRI was clear. He had an indication of high blood sugar and low potassium. He had the stutter almost completely disappear later that day. He had an EEG done three days later on Friday. That indicated that he had a normal EEG awake and asleep. This Monday the stutter came back full force and has not gone away. He has had arm twitches a few times since Monday and last night he woke up feeling sick to his stomach. He ended up having diarrhea. He also had a headache. I am at my wits end. The doctor implied it was stress, not wanting to go to school, etc. He likes school and he said there was not any excessive stress. The doctor said it would go away on its own. The doctor is referring him to a speech therapist. This does not make sense to me. Please let me know what you think is causing his problems. Thank you.