###Human: Why is there stomach pain and vomiting sensation with missed periods? ###Assistant: Hi. How are you doing? Hope you had the tests for pregnancy recently, as you have missed periods for two months. If they are recent and surely negative, then this pain is the tendency for impending periods. For a young lady of your age, BMI of 17 is very low. For your height of 158 cms, expected weight is 58 to 62 kg. A minimum weight is required for regular periods. When you have weight, fat in the body, it is a store for a time of possible emergency or fasting, etc. Now your body is running short of energy source, so it is not spending it on periods, which is like a drain out of energy.  To have periods now, have any of the oral birth control pills or contraceptive pills or 21 pills packet of tablet Novelon or Ovral-G or Dear 21 or Intimacy plus 3 or Duoluton-L one tablet twice a day for 10 days (throw away the 21st pill), no matter what the cause is (except pregnancy) you will have periods within 7 to 10 days. You can keep having the same pills cyclically for 3 to 6 months to have regular cycles and take that time to improve your health. I do not advise you to have binge eating and put on weight. Have lots of fruits, vegetables, high protein diet like egg white, milk, meat (not red meat), sprouts, protein drinks, so on. Your improving health will help you in the future to have a healthy pregnancy too, poor health can affect pregnancy in future causing abortions, growth restrictions in baby, preterm labor pains.