I've been having heart burn since 4am. also some pain in my lower stomach. i'm on the pill so i know i can't be pregnant or could i be?

Preg. unlikely, but: Birth control pills are not 100% protective against pregnancy. If worried, one can check a test (cheap and available in stores). A urine pregnancy test done correctly gives a reliable result 3 weeks after sex (3 weeks after when conception might have been). If done sooner, a positive result is likely real, but a negative result may be due to testing too soon, and therefore lead to a repeat test.

Symptoms: appear to suggest GERD and Gastritis an examination by a physician, possible and management is neccessary