Orange spotting a week before period

I'm concerned, about a week and a half ago for a short time, about 3 days. I started spotting, which has never happened to me before. The blood was orange and watery. This only lasted for a few hours each day, but by the last day it happened the color changed and got dark almost black in color. Well now, I'm a few days late for my period, and I'm worried that I might be pregnant. My co-worker told me that it could have been implantation bleeding. I'm not on birth control, and my boyfriend had been inside me with out a condom for a small amount of time about a week or less before the spotting happened. I don't know if its related or anything but I’ve been having chest pains and getting dizzy and sick feeling like I'm going to throw up. Any help would be greatly appreciated.