My 8 Week Old Puppy Has CONSTANT Diarrhea, I Gave

My 8 week old puppy has CONSTANT diarrhea, I gave his first worm med at 6 weeks, he had round worms bad, I see no signs of the worms anymore . I'm supposed to give him another dose tomorrow. I feed him dry food and plenty of water so he doesn't get dehydrated, every time he goes it's straight diarrhea what do I need to do? Thank you Danya