My Husband Has Been Taking A Cough Medicine With Phenegran

My husband has been taking a cough medicine with phenegran and the Dr. told him to take Benadryl also. Found out today he has really bad strep throat. He has had really bad bronchitis for about 7 days and that is why the cough medicine. He has had problems breathing and had anxiety. The Dr. prescribed Ativan for his anxiety. He has had bad reactions in the past to phenegran - some hallucinations and confusion and insomnia - weird dreams. He is having the same symptoms. How long would it take the phenegran cough medicine to get out of his system and could it react with the Ativan. His speech is real slurred and his is quite confused.