Implantation bleeding?

Hi, my gf and I had protected sex on December 5th, I didn’t *** at all. I couldn’t get hard enough, so we kept trying stopping and trying again; and changing condoms each time I tried putting it in, but ultimately nothing. I’m worried there was some pre-*** involved tho. Because, her ovulation was December 7th. And on December 10th she said she was experiencing spotting.... so now we are both worried. Could this be implantation bleeding or maybe ovulation bleeding?

She said this happened to her once before 5-6 months ago when it was really cold outside, but nothing happened. 

Please help with any opinions.