My Dog Has No Energy For The Past 2 Weeks Appetite Is Fine?

Dogs like people have different energy levels depending on the circumstances outside.  Ever notice that if rainy day, or change of seasons will affect your energy level either causing you to need more sleep or the opposite.  If it is a female, and not fixed, as they say, have you been letting her run around unattended.  There is a slight chance she may be pregnant.  But don't jump to conclusions, wait a few days and see how the animal is acting.  Could be something as simple as it got a cold and like people, needs to rest.  If the dog's condition takes a turn for the worse, ie. Lethargic, acting sickly, stops eating etc. Then get checked out by the vet.  My friend has a dog, and a few people in the house went on holidays, the dog became lethargic, home sick or lonely.  It is amazing how much dogs behaviours are similar to ours

Is your dog a female? If so perhaps she is pregnant.