With a 2-month-old dog, we cannot wait long to take action on diarrhea. This is due to the fragility of a puppy, as they can enter hypoglycemia very quickly, in addition to the fact that dehydration and hypothermia can occur, thus completing what we call the newborn triad.
The causes of diarrhea in a dog of this age can be many; they range from food recklessness, which is when the animal eats what it shouldn't, to a viral condition that, in this case, is more serious.
Puppies usually eat objects, this picture is called "foreign body" and most of the time the treatment is surgical. Verminosis is very common in puppies that have not yet been dewormed. What you must remember at this time is not to wait, take him to a veterinarian as soon as possible and, if necessary, even leave him hospitalized.
Hope this helps