implantation

is it possible for implantation bleeding to last almost 4 days? I wasn't really paying attention to the color so I'm not sure if it was a period or implantation. I was due for AF on the 21st of Nov. and got it the 17th and it ended on the 20th. my periods are normally 6ish days. my husband and I had sex a few days after the bleeding stopped and I started bleeding a little during the sex. a few days later, I started feeling bloated to the point I couldn't keep my pants buttoned because they felt too tight, my feet were freezing cold and I had shoes and socks on, and I couldn't sleep and was constipated. ever since that day, I'm still constantly feeling bloated and my upper abdomen is hard but below my belly button is still jiggly. lol. but I've been getting random feelings of nauseous, random headaches, lower back pains, feet still get cold at times (idk if that's actually a symptom), and I get random points where I'm so tired I could pass out. I've taken tests but all negative. am I pregnant or is something else wrong?