Could I Be pregnant?

Patient: I am very scared that I may be pregnant! I had protected sex and i am on birth control. the condom did not break and nothing went wrong. two weeks after intercourse i had light spotting, that turned heavier and went light again- like my periods. it lasted about 4-5 days. it is now 4 weeks after intercourse, and i am supposed to be on my period today. i am having some light cramping and some upset stomach problems. but nothing major. could i be pregnant??