Implantation Bleeding?

I had sex on March 26th and the condom broke. Today marks the second week. I thought I got my period early because I started bleeding but it was dark and lasted for 2 days when normally my period lasts 5. I read that implantation bleeding happens on 20th day of your cycle, which would have been the 4th. I've been incredibly nauseous, even before the bleeding. My next period is supposed to be in a week, April 16th. Would it be too soon to test?