Tummy is sore, achey, full- also had what feels like awful period pains coming and going all month. have just begun taking the pill, is it the cause?

Could be: Hormonal changes that occur following initiation of a contraceptive can certainly cause pelvic discomfort. Usually these symptoms improve with time, but talk to the healthcare provider who is prescribing the contraceptive. Often a different formulation will be better tolerated.

OCP side effects: All of these symptoms can be caused by starting an oral contraceptive pill. The symptoms may get better with time, but for some women, they continue to be a problem. If the discomfort doesn't improve by the end of the second month, the prescribing doctor needs to know. She/he might prescribe a lower dose OCP that is still effective for birth control but that might have fewer side effects.