Personally I always get my wormer from my vet. They will always give you something safe and if your pup has a reaction they are available to help. I learned that lesson decades ago when we used to do our own vaccines and my pup blew up like a balloon. Never again.
Pups seem to thrive on eating every bit of poop they can find. Stopping them can be a big challenge and I often give up micromanaging the issue and randomly yell "stop eating poop", which doesn't necessarily help, but makes me feel like I'm doing something.
Pups in general can have looser stools, especially later in the day. I read it's because of activity. If it's consistently loose you should have a fecal done to check for cocidia and giardia. Some foods higher in fats can also cause loose poops.
