Is it implantation bleeding?

I'll be 40 in 3 weeks. I track ovulation and this month I got my lh surge and ovulation cramping 3 days early. That meant that we essentially had sex when a doctor would recommend it if we were ttc. Now I am desperate to find out if I got pregnant. Lh surge happened Monday-Tuesday. On Saturday (yesterday) I had spotting when I wiped. This seems early for implantation to occur. I looked up other causes of bleeding and none of them seem to apply to me. Has this happened to anyone else? This would be my 5th pregnancy. I have 3 children.