Hello, Thanks for asking your query at health care magic. I understand your concern. I am Dr Alok Sinha, MD Psychiatry from India. I will try to help you with best of my effort. It is true that person suffering from Bulimia Nervosa have habit of vomiting repeatedly. Due to forceful vomiting sometimes there may occur tear of lower end of gastro-esophageal junction. It is generally associated with blood in vomiting. But this is unlikely in your case as there is no history of blood in vomiting. At the time of forceful vomiting, there is sudden contraction of abdominal muscles. This may lead to muscle strain, causing sharp sudden pain at abdomen. This has exactly happened with you. You also accept having pain on stretching arm. This further goes in the favour of having abdominal muscle strain, because due to stretching of arm abdominal muscles get stretched which may cause pain at the strain site. Intestine does not get stretched by stretching of arms. So be assured, there is nothing serious, but you must treat the cause, the Bulimia Nervosa. I strongly suggest you to consult a psychiatrist at the earliest, who may treat you with some medicines and psychotherapy to treat your eating disorder. I hope it answers your query. I wish you all the best.