go to the doctor or er and ask for a blood test so they can check your hcg levels and tell them what happened.
It's possible! Your body is just confused by the foreign body and needed to release another egg. Hopefully u dont get one in 28 days that's when I would worry! This happened to me at 14 weeks!
It's possible to have your period throughout your whole pregnancy for some women. But just in case of possibilities of miscarriage or ectopic pregnancy go to your doctor whenever you have any pain or bleeding that is more than spotting. Good luck sweet heart I hope everything is okay. : )