Weird spotting

Okay so period was 15th through 19th. You can see on screenshot all the days we had sex. However on the 24th I started light spotting. (Only when I wipe! Nothing on pad or tampon). So today is day 5 of this super l ight pink spotting. Also been nauseous for about a week and sore breast had me thinking implantation bleeding......but 5 days?Any ideas as to what this is?