Thanks for contacting askthedoctor.com
If the pregnancy test is negative and you have been regularly mensturating then it is not pregnancy. It is possible in women who have a lean built that even gastrointestinal peristalsis may be perceived as substantial movement mimicking fetal. nausea and mood swings may be part of premenstrual syndrome which also involve bloating , uterine cramps and headaches.What you are going through is premenstrual syndrome and your menses are likely to initiate in few days.
I hope i have answered your query,
wishing you good health,
These Q&A’s are for educational purposes and should not be relied upon as a substitute for medical advice you may receive from your physician. If you have a medical emergency, please call 911. These answers do not constitute or initiate a patient/doctor relationship.