That is NOT an overdose. A dog may have 5 mg per lb of aspirin.
It sounds like it just disagreed with her.
She can have Immodium, kayopectate or any OTC at www.wolfdancer.org/health scroll down for products and dosages.
She may have a bad tummy ache. I would pick up any dog food.Try a small amount of boiled chicken with all fat drained off, chop meat , or baby food with no onion, beef, turkey, etc add cooked white rice or infant rice cereal @ one tablespoon per meal.
Go very slow so she does not throw it up.
Dogs get dehydrated and hypoglycemic very easily from diarrhea.
Add unflavored pedialyte to her water 50/50 to hydrate her and balance her electrolytes.
Put a drop of pancake syrup on her tongue to raise his blood sugar in case she is a bit hypoglycemic. That should perk her up.
Keep him on that very light diet of boiled chicken or chop meat for 48 hours after the stool is normal.
Also give her one teaspoon a day of plain yogurt to keep "good" bacteria in her system.
If she develops any abdominal pain, bloating, constipation or cannot keep anything down she needs to be seen by a vet.
Please let me know how she is doing. I will always be here for you
I hope your baby feels better very soon..