It does sound like your dog is having an allergic reaction to a bee, scorpion, or snake bite. Your dog needs immediate veterinary attention. Many allergic reactions are mild and self-limiting; resolving in 12-24 hours. Your dog has been sick for 3 days--he needs more aggressive treatment especially if he is vomiting--you cannot use oral medications in a dog that is vomiting. Please have him seen by a veterinarian so he can be treated. Allergic reactions and secondary complications can be life threatening.
