Implantation?

So I had sex for the first time about 6 days ago (with a condom and he pulled out). Flo says I ovulated 9 days ago, however there were no indicators of this at all (usually I get a pain in one side and lots of egg white cm). Today I noticed the tiniest bit of pink discharge in my underwear. I have never ever spotted even slightly before so this is completely new to me. When I wiped it had gone completely. I am now experiencing quite a bit of back pain and some mild cramping which has come on suddenly. It’s 8 days until my period so I’m just confused as to whether this could be implantation bleeding? I’m going to get a test tomorrow in case but might have to wait a few days before using it. Has anyone had an experience like this and what was the outcome?