a day and half period with negative test?

Hi,
Welcome to ehealthforum,
The symptoms (abdominal cramps, headache, sore nipples, mood swings, shorter & lighter period) that you describe could indicate pregnancy chances if you have messed up your regular birth control pill intake or have missed taking 2 or more than 2 pills or taken them late by more than 2-3 hours on 2 or more than 2 occasions (you will not have the effective protection from your birth control pill use). Look out for development of any other new symptoms if pregnancy is suspected. If you suspect chances of pregnancy, consider visiting your doctor/gynecologist at the earliest for thorough examination (to confirm pregnancy related changes/signs in body) and blood/serum HCG level test (to confirm/rule out pregnancy accurately). Be in regular monitoring and follow-up with your treating doctor/gynecologist and report any new/abnormal symptoms immediately. Take adequate rest. Drink plenty of water. Maintain healthy diet.
Take care.