I got old period blood on his shirt 🤢

This guy I've been seeing for 2 months and I were having sex and I recently just had my first period on nexplanon and it lasted 8 days and today and yesterday brown stuff has been coming out which I'm sure is the old blood but I thought it had stopped this evening. Well he kept his WHITE shirt on and it's a really nice soccer Jersey and we switched into missionary and after we finished I looked at his shirt and the brown stuff was alllll over the bottom and I'm just like 🤦🏽‍♀️ nooo I'm so sorry and he just joked it off but I'm sure hes like wtf is this and I didn't feel like explaining and ... yeah idk just idk . So a question, is that what spotting is? Or is this still considered my period? It's all brownish and its been coming out for 2 days.

*edit

Ok guys I texted him letting him know it was my period and to soak in cold water I feel so bad 😂