Your pet needs to be under the care of the best "seasoned" Vet in your area. Best to find older Vet with some large animal background, such as horses, farm animals, since they have best experience in what your describing.

For any serious condition such as MRSA and like, buy a pack of 30 ALLICIN / 180 mg each. Can be found on net, sells for around $24.00 plus shipping. Animals 10-40 lbs., give AM & PM one capsule (in cheese or treat) twice daily. 40 lbs. to 70 lbs. Give same, but three times daily. Over 70 lbs. give four capsules, 1 every four hours.