My 2 yr old American Dingo/Carolina Dog is in great health. I have not changed his diet. He just decided not to eat this morning. I can hand feed him his dog biscuits and he will eat them hesitantly... he smells the dry food and walks away... has loose stools... started today. I take him to daycare sometimes and he was fine (tired) but fine on Friday. This started today (Sat)... he is resting a lot and tired but happy otherwise... drinks water fine... he has never not wanted to eat no matter how many times he went to daycare... what should I do?

You should really take him to the vet to be sure he has not contracted anything or has any kind of parasite.

As I said at https://www.askmehelpdesk.com/dogs/information-articles-our-dogs-expert-labman-53153.html#post254171
Most dogs that won't eat are sick and need to see a vet, or are over fed. Even in that case, I suggest you have a vet comfirm your judgement.

Your dog may have parvo especially if his stool is bloody and it seems depressed