There are several different reasons why your dog may be rubbing his face, either with his paws or against the carpet. Causes may include:
Allergy
If your dog has an allergy of some sort, like to specific medications he may be taking or to a plant he was nosing around in while outside, he may have facial swelling leading to a need to rub the face.
Mites or Fleas
Mites and fleas can cause irritation if your dog has a large number of them on his face. He may be scratching his face repeatedly or several times a day, and his face may swell causing him to rub it.
Blepharitis
Blepharitis is an inflammation of the eye, namely the outer skin and eyelids. It can cause your dog to paw at his eye or eyes repeatedly. Make an appointment with your veterinarian as soon as possible if your dog shows signs of any eye inflammation.
Trauma
Bee stings or snake bites can cause itching, burning, and swelling of the face. If your dog has pain or irritation of the face due to a sting or other trauma, he may need a visit to the clinic.
Dental Condition
Just like humans, if your dog has an infected tooth or gum area, he may have facial swelling on one side. In some cases, swelling may not be evident but rubbing of the face is a symptom of the pain. A tooth abscess can be very painful and requires immediate veterinary attention.
Ear or Eye Irritation
If your dog has an ear infection or eye irritation (or infection) he may paw at his face repeatedly. He will most likely be experiencing discomfort, and pawing at his face will be a way to help him ease the pain. There are many different causes of these irritations, and most eye and ear irritations can be cleared up with the proper examination and medication prescribed by your veterinarian.