Period or something else?

ok ill try to make this a short as possible i had sex last month and the condom ended up breaking i took an EC pill but i messed up on the second pill and i took it four days after i took the first one. i was a little over a week late on my period and i was feeling really nausea's my breast where really sore and i was getting headaches which nausea and headaches i never get these as pms symptoms.i took a pregnancy test but didn't realize it expired a year ago but it came out negative.i never got any PMS symptoms and well this morning i started getting cramps and they where so painful that i was breathing like i was giving birth (i never had cramps like these before) and then i went to the bathroom and i was bleeding but its like a really dark brown with a little red blood in it (TMI sorry) well i also threw up but it wasn't alot and it was kinda acidy and clear (TMI again.) im still nausea's and my breasts are still sore and its just weird because i never ever get headaches or nausea during my period and once i get my period i usually only have cramps and bloating and i don't know if there's something wrong or if its intense because of my late period please help!!!