it would be impossible to determine a specific cause of monthly bouts of vomiting/stomach pain and lack of menstruation for three years blindly over the internet. you will need to see a gynecologist for a thorough medical history and examination. there are multiple possibilities and they cannot be sorted out by this forum.
vomiting no period not pregnant. since i lost wright for 3 years ago i didnt have period eversince. today i am 162 cm and 42 kg. also i have stomach pain and vomit at least once in a month. what could it be?