Hi! Good afternoon. I am Dr Shareef answering your query. The pain in the left side of your abdomen could be due to gastritis caused by the possible intake of any pain killers consumed by you for the headaches, etc. If not , it could be due to any intra-abdominal inflammation for which a physical examination along with blood test like a CBC, LFT, serum amylase and serum lipase would have to be done, specially if you consume alcoholic beverages. Till then you could go for some anti spasmodic and a proton pump inhibitor drug. A word of caution on birth control pills: All the precautions including birth control pills are not 100% fool proof in protection against a pregnancy. If I were your doctor, I would also go for a serum HCG determination and an ultrasound abdomen to rule this out, and then consider your symptoms of breast pain, nausea and fatigue etc not to be due to a pregnancy, if these tests were negative. If positive,the whole management plan would change accordingly. I hope this information would help you in discussing with your family physician/treating doctor in further management of your problem. Please do not hesitate to ask in case of any further doubts. Thanks for choosing health care magic to clear doubts on your health problems. I wish you an early recovery. Dr Shareef.