What are some symptoms for anorexia that if it gets bad enough you have to go to the ER?

Can I ask why? I need a little more info please.

People who have anorexia try to hide their condition, so others may not notice the signs and symptoms of their disorder. Symptoms in teenagers can be even harder to detect because some warning signs look like normal adolescent development. Some people with anorexia exhibit many of the following warning signs and symptoms, while others may exhibit only a few.

Physical signs and symptoms
Dramatic recent weight loss unrelated to an illness
In women, missing three consecutive menstrual periods
No energy or complaints about feeling cold all the time
Dry, lifeless hair; brittle nails, poor skin tone

Behavioral signs and symptoms
Strange eating habits, like restricting certain foods or drastically reducing how much food you eat.
Excessive and/or compulsive exercising
Complaints about being fat when obviously not
Frequent weigh-ins and over-attention to tiny fluctuations in weight
Always checking in the mirror for body flaws
Excessive trips to the restroom or regular use of laxatives

Social signs and symptoms
Pretending to eat or lying about eating
Making excuses for not eating or for running to the bathroom
Wearing baggy clothes to cover up gaunt appearance
Apathy, withdrawal from social life or moodiness

Cuz I've had a stomach ache n really bad headaches all day

Anorexia Nervosa is a mental health disorder. You very well could have the flu.

Girls with anorexia don't eat. Do you have anorexia?

If you are anorexic you get nauseous or sick when you try to eat even like a half a sandwich. Don't let it ever get to that point.

Common feelings and actions that are linked to anorexia nervosa include:

Having an intense fear of gaining weight.
Restricting food or types of food, such as food that contains any kind of fat or sugar.
Weighing less than 85% of your expected body weight. (In a child or teen, losing or not gaining weight during a growth spurt is a concern.)
Seeing your body as overweight, in spite of being underweight. This is called having a distorted body image.
Overexercising.
Being secretive around food and not seeing or wanting to talk about having a problem with eating or weight loss.
Some people who have anorexia also make themselves vomit or use laxatives or diuretics to lose weight (bulimia). Breakdown of the enamel on the teeth is a common symptom of long-term vomiting.

Common physical signs of malnutrition from anorexia include:

A low body weigh
Constipation and slow emptying of the stomach.
Thinning hair, dry skin, and brittle nails.
Shrunken breasts.
Stopping or never getting a monthly menstrual period.
Feeling cold, with a lower-than-normal body temperature.
Low blood pressure.
A slow heartbeat (fewer than 60 beats per minute).
Not feeling pain as you normally would.
Purplish skin color on the arms and legs from poor blood circulation.
Swollen feet and hands.
Yellow-orange skin, especially on the palms of the hands.
People who have anorexia often develop rituals associated with eating. These may include:

Developing special ways to eat food, hoarding food, collecting recipes, and preparing elaborate meals for other people but not eating the meals themselves.
Spending a lot of time cutting and rearranging food on their plates to make it look as though they have eaten. They may also hide food or secretly get rid of it during meals