Laying around is not good.
It could be heat, it can also be pyometra -- dangerous. Two types, open and closed. This is where the uterine horns fill with pus. It will kill the bitch if it is closed as it will burst. If it is open, then she will be leaking. Blood sounds like it is a heat cycle, but she may be sick as well.
If you feel she is lethargic, moreso than can be explained by being in a new home, etc., check her vitals: temperature, refill, dehydration and call your vet for a full check up.
Jenna, RN CGC & Babs, CD RA CGC HIC
Heidi, RA CGC
SG3 Odessa, SchH1, Kkl1, AD
Ninja, RN CGC & Milla, RN CGC
Joy, Star Puppy, RN CGC
Dolly CGC & Bear CGC