Hi hon, I know this is scary, pero please go see your doctor or go to the ER today, bleeding with pain like that, especially twice, needs checking ASAP para ma-rule out kung ano talaga ang nangyari. Could be a lot of things, your IUD, the activity, or something else, pero hindi ko kaya i-guess yan for you, at kailangan mo ng proper check-up para safe ka. Hugs, and let me know how you go?