Implantation Bleeding or Something Else?

[cnote]

Hi all, I'm 36 and my husband and I are trying for a second kid. We have a 2 1/2 year old son already. We actually aren't trying per se, just "not preventing" and seeing what happens. When I got pregnant with my son, I felt a sharp stabby sensations in my abdomen 2 days after sex, and then had spotting the next day. I never spot inbetween periods, so I KNEW it had something to do with conceiving but everything I read said implantation bleeding happens days, or even weeks after conception. Anyway, my husband and I had unprotected sex twice in the last week and yesterday I got the same stabby feeling and spotting like I had with my son. Again, Google tells me it can't be implantation bleeding because it's too early...has anyone else experienced this?