Had sex multiple times over past two days. Last time started bleeding a LOT. After 24 hrs still bleeding, having burning and pain.

Exam ASAP. You may have a vaginal tear of bleeding from aggressive sexual relations. Please call your GYN for a thorough pelvic examination. I would suggest that you call today.
Vaginal bleeding... ...that is abnormal in any way needs to be professionally evaluated. Given the large amount, see a doctor ASAP. Genital burning and pain, or pain in lower abdomen, also need immediate exam. Various STDs are possible, including herpes, gonorrhea, chlamydia, pelvic inflammatory disease (PID), as well as injury, hormone problems, etc. Maybe more than one problem. See your doctor today. Good luck!