Implantation bleeding?

Brittany
So lately I've been really moody and emotional, nauseous ALL the time, but haven't gotten sick. My appetite comes and goes. I've been really fatigued and lazy feeling. I (thought) had a period a week ago. It lasted the normal length but it was mostly light. One day I wouldn't bleed at all, the next I'd be bleeding like normal. I figured all my symptoms were from stress. A friend of mine mentioned implantation bleeding. I googled it like I always do and the dates it gave me made sense with a time I had unprotected sex with my boyfriend. It said it can last up to 7 days, and my "period" was 6. I took a test but it was negative. Anything similar happen to you guys?