What is wrong when i have headache, backache, nausea, upset tummy and tiredness? i am on the pill for 2 years now and i skipped my previous period and then started a week early with my next cycle and now when my period needs to come, it didnt.

Many possibilities: Pregnancy is a common cause of a missed period. If not pregnant, other causes of a late or missed period include: having a significant illness, excessive weight loss or weight gain, increased exercising, emotional stress, traveling, medicines (especially hormone or birth control pills), hormonal disorders, etc… A visit to one’s doctor is a good idea if symptoms are bothersome like in this case.