Why have I been vomiting for the past 9 months uncontrolably?

acute gastritis
central causes (signals from the brain)
association with other illnesses remote from the stomach
medications and medical treatments
mechanical obstruction of the bowel
Acute gastritis
Acute gastritis (gastro=stomach + it is= inflammation) is often caused by an offending agent which irritates the lining of the stomach. Examples of these include:

Infections: Infections are often the cause, whether it is a common virus or an infection that is contracted from travel. There may be associated crampy upper abdominal pain, fever ,and chills may be present. Common viral infections include noroviruses and rotavirus. Parasitic infections often are associated with diarrhea but may also have a component of nausea and vomiting. Infection by bacteria in the Helicobacter family (like H. Pylori) can also be the infectious agent.

Stomach flu: Stomach flu is a non-specific term used to describe vomiting and diarrhea associated with a viral infection. It should not be confused with influenza, whose symptoms include fever, chills, cough, and myalgias (muscle pain).

Food poisoning: Food poisoning may cause significant vomiting and usually is caused by a bacterial toxin. Symptoms begin within a couple hours of eating contaminated or poorly prepared food and may last for 1-2 days. Sources of food poisoning include Salmonella, Campylobacter, Shigella, E. coli, Listeria, or Clostridium botulinum (botulism).

Other stomach irritants: alcohol, smoking, and non steroidal anti-inflammatory medications such as aspirin and ibuprofen may irritate the stomach lining.

Peptic ulcer disease: Peptic ulcer disease can range from mild irritation of the stomach lining to the formation of a defect in the protective lining of the stomach called an ulcer.

Gastroesophageal reflux disease (GERD, reflux esophagitis): Nausea or vomiting is also associated with irritation of the lining of the esophagus

Headache: especially migraine, is commonly associated with nausea and vomiting.

Inner ear: Motion sickness, labyrinthitis, benign postural vertigo, or Meniere's disease

Head injury: Any illness or injury that increases the pressure inside the skull can cause vomiting. This rise in intracranial pressure may be due to brain swelling from trauma (for example, concussion or head trauma), infection (meningitis or encephalitis), tumor, or abnormal electrolyte and water balance in the bloodstream.

Noxious stimulus: Certain smells or sounds can cause centrally mediated nausea and vomiting. Whether it is the pain of a broken bone or the emotional shock of observing an event, vasovagal events can cause significant symptoms. In a vasovagal episode, the vagus nerve (one of the nerves that helps control basic body functions like heart rate, breathing, and blood pressure) is overly stimulated and cause the heart rate to slow and blood vessels to dilate. This decreases the blood flow to the brain and causes fainting, known as a syncopal episode.

Heat related illness: For example heat exhaustion, extreme sunburn, or dehydration.

Association with illness

Diabetes: Persons with diabetes may develop nausea because of gastroparesis, a condition in which the stomach fails to empty properly and is likely due to the generalized neuropathy (failure of the nerves in the body to send proper signals to and from the brain) that is a complication of the disease.
People with diabetes can also develop nausea and vomiting should their blood sugars become abnormally high or low (hyperglycemia or hypoglycemia) because the sugar and insulin balance is disturbed.

Diseases or illness:

Many illnesses associated with the intra-abdominal organs have symptoms of nausea and vomiting. These include digestive organ diseases, for example:
hepatitis,
gallbladder disease,
pancreatitis
inflammatory bowel disease
kidney diseases (for example, kidney stones, infection, kidney failure)
some forms of cancer.

Vomiting as an atypical symptom of another disease: Some illnesses will cause nausea and vomiting, even though there is no direct involvement of the stomach or gastrointestinal tract.

Heart attack victims may experience nausea and vomiting as an atypical presentation of angina, especially if the myocardial infarction affects the inferior or lower part of the heart.

Lung infections, for example, pneumonia and bronchitis, may also cause nausea and vomiting, especially if the area of lung involved is near the diaphragm, the muscle that separates the chest form the abdomen.

Sepsis: An overwhelming body infection spread through the bloodstream may also be associated with nausea and vomiting.

Eating disorders: Patients with bulimia will have self-induced vomiting, purging as part of their psychiatric illness.

As you have read there are many causes, we must find yours to start with the proper treatment.

What has your doctor told you?

Are you taking meds, if so which one (s) ?

Have you been to the doctor, have you had tests done, which ones?

What do you think triggered this?

Can you please provide us with more information--details?

Can you also please make the time to answer my Q´s?

Thank you.

Take care