He is only about 5 lbs, 61/2 months old. He got into his bag, which had a supply of dewormer in it. He ate it all yesterday. Now today, he has diarehha, isn't eating much, and is acting funny.. Help! Is he all right?

What kind of wormer was it? Do you remember the name of it?

You should really be calling your vet. Some wormers are an actual poison that will harm your pet. I would almost call this an emergency.

I would call and ask your local vet if the dewormer is fatal to your dog. Depending on how much he ate, he may be okay, but if he ate more than what is suggested for his weight, he may need to go see a vet.