Please note that it is not a good idea to attempt to diagnose or label a friend or family member. Only a mental health professional can diagnose an anxiety disorder, as many disorders have overlapping features, and can go together with other types of mental health difficulties. However, if you notice signs of anxiety, or just feel that something is not quite right with someone that you care about, it's a good idea to reach out to ask the person how they are feeling. You could start with something neutral and supportive like, "It seems like you haven't been quite yourself lately. Is there something going on that you want to talk about?"
Social Anxiety Disorder;Fear of social situations in which the person is exposed to unfamiliar people or to possible scrutiny by others. The individual fears that he or she will act in a way (or show anxiety symptoms) that will be embarrassing and humiliating, often times leading to avoidance of social situations and severe distress when participation in social situations can't be avoided. 
Researchers have conducted both animal and human studies to pinpoint the particular parts of the brain that are involved in anxiety and fear. Because fear evolved to deal with danger, it sets off an immediate protective response without conscious thought. This fear response is believed to be coordinated by the amygdala, a structure deep inside the brain. Although relatively small, the amygdala is quite complex, and recent studies suggest that anxiety disorders may be associated with abnormal activity within it.
Only 16, Caroline, had her first panic attack a year ago. Her mother was dropping her off at her summer job at a local school when, without warning, a full-blown panic attack engulfed her. “My heart started racing and my body felt so hot. I started to sweat and shake uncontrollably. My vision became distorted and my body felt limp, like a wet noodle,” she says. For 20 minutes, until the panic attacked passed, Caroline refused to get out of the car. Her mother didn’t know what to do.
Agoraphobia is often comorbid with panic disorder — meaning people often suffer from both conditions at the same time. It's an intense fear of not being able to escape whatever place you're in, and can often lead to an avoidance of leaving the house. People with agoraphobia can fear situations where this anxiety might flare up, and typically don't feel comfortable or safe in public, crowded places.
Characterized by a preoccupation with the belief that one's body or appearance are unattractive, ugly, abnormal or deformed. This preoccupation can be directed towards one or many physical attributes (e.g., acne, hair loss, facial features). Muscle dysmorphia is a subtype of this disorder that is characterized by belief that one's body is too small or insufficiently muscular.