Possibly, he might be going through psychotic episode. just to rule out this, take him to psychiatrist. immediate psychiatric attention is needed.

I understand your concern towards your friend. He seems to be suffering from psychotic symptoms including hallucinations, delusions and irritable behaviour. To attribute thyroid as the contributing problem, the levels of TSH,T3,T4 should be found significantly abnormal. If not then it could be independent psychosis. However it is easily manageable with appropriate treatment. Some counselling sessions along with medical help might be useful for him. I would also be more than happy to help you with that if you are looking for online assistance. You can directly consult with me through Practo as needed. Online chat consultation is available.