Friend's dog and Medication question

One of my friends has a 3 year old Sheltie. She has been at the Vet Clinic for several days because of a kidney problem the Vet says was caused by a toxin of some kind. She had been boarded at a kennel while my friend was away on a trip. Actually both of his dogs were sick when he picked them up and have been at the clinic. While there, they were given lots of fluids, antibiotics and Clavamox. They are much improved and he took them home this afternoon. The older Sheltie seems fine, but the 3 year old is acting strangely, bumping into furniture, etc. My friend thinks she is blind, but after reading some side effects of the Clavamox, I believe she may be confused and disoriented. Those were some of the side effects listed, along with facial swelling, which she also has.
My friend is beside himself with worry...he is taking her back to vet tomorrow.
Just wondering if anyone has had experience with anything like this?
Thanks