Hi thanks for your question.
Most probably you are suffering from gasritis that is inflammation of stomach and/or an ulcer in stomach.There are many causes of gastritis
and commenest cause is infection of stomach by a bacteria called H Pylori.Other causes include cigrette smoking
,spicy food and alcohol.Frequent vomitting and unable to eat can lead to dehydration
leading to decrease in blood pressure and weakness I would suggest you to consult a gatroenterologist or an internal medicine specialist who may be able to perform to perform upper G I endoscopy
on you to confirm or rule out gastritis and ulcer in stomach as for cause of your symptoms.Avoid alcohol and abstein from smoking if you are using any one of them.You can take antacids and proton pump
blockers like pantoprazale.
Hope this answers your question.