Spotting

Bailee • Bailee&Clayton, hopefully soon + Baby
So I need help ladies. I had dark red/brown spotting for about 4 days. I had sex with hubby and it turned a lighter pink for a bit but then went back to dark color. It wasn't that much, never enough to have to ware a pad of tampon, just when I wiped. Can this be implantation bleeding? And if so when should I test??