oh, girl a puppy of 5 weeks is very much still depending on mom for teaching him lots of things and in my case they are just weaning off mom's milk, he should sleep, eat,poop, pee, play a little and sleep,again.
even at 8 weeks they take naps every couple of hours. my puppies stay with mom until they are 12 weeks. keep him warm and fed, also the runny poo is the change on his diet, you need to have plain pedialyte at home, if you see that he's skin is not bouncing back when you pull on it a bit on his back he is dehydrated, you need to feed him 5cc's of pedialyte every 2 hours until he is back to normal, other than that you must run to the vet, he is VERY young and delicate..
hugs,
Carmen in nj