Thanks for the query.There are different causes for the symptoms you have given but one of the causes of this could be an ectopic pregnancy. This type of pregnancy can occur even when a person is on contraception and most women are unaware of the pregnancy. Here the fertilized ovum is implanted in an area other than the uterus and is non viable. It is a life threatening surgical emergency as it could rupture at any time, leading to shock and may even lead to death. Hyperthyroidism could also lead to the above symptoms, in addition it will also have symptoms like increased appetite, loss of weight, heat intolerance etc, There is also a condition called struma ovarii where a mass of thyroid tissue is found in the ovaries causing these symptoms like pressure/pain in abdomen,nausea,irritability, etc. Anorexia nervosa, an eating disorder can also lead to similar symptoms. It could also be due to Pelvic inflammatory diseases like oophoritis, salpingitis, tubo ovarian abcess etc which again have life threatening complications. Since you have not given us the details like the age, marital history, duration of these symptoms, contraceptive practices etc. we would suggest you to visit a gynecologist and a General Physician to get an Ultrasound and other tests done and for an examination to rule out the possibility of these conditions.