Emergency! GOT CAUGHT ! HELP ASAP

So long story short me and my bf had sex at his place today and I'm on this new birth control and my period hasn't stopped yet so there was a little blood on the condom .. My beef threw it in his trash but his mom came in later today and I guess looked through his trash (ew) and found it and he can explain the condom but he can't explain the blood.. WHAT DO I DO TO HELP HIM ? His mom doesn't know he has a gf and there's kinda bad history !! Please Help !! How do I explain blood without saying its blood