Pregnancy scare ?

So me and My husband had unprotected sex for about 5-6 days straight sometimes 2 times in one day .Our last time having sex was August 12 and it takes 18-24 hours for the sperm to reach the egg on a fertile window which is when we had sex. I’m now having back pain and lower stomach pain ..it felt exactly like implantation pain. I know I sound like a hypochondriac but I’m now experiencing mild nausea..we have 10 more days for my period to arrive and it’s been 6 days since we last had sex..thoughts??