The group of mental health professionals who earn either a ph. d., ed. d., or a psy. d. and then diagnose and treat mild and severe mental and emotional problems are called:

they are called Clinical Psychologists

Explanation:

Clinical psychologists are professionals that study Clinical Psychology which is a broad branch of psychology that focuses on diagnosing and treating mental, emotional, and behavioral disorders. Some of the more common disorders that might be treated include learning disabilities, substance abuse, depression, anxiety, and eating disorders.