It is important to give priority to the health of your animal, as it is a living being that depends on you. Probably her dog when she went to be groomed already had an advanced dermatitis that was not possible to see due to the coat on top.
A grooming is unlikely to cause injuries like the ones you are describing immediately. Removing hair and bathing may have irritated the skin and worsened dermatitis, as in this case dermatitis is probably an infectious process, the animal starts this process of losing its appetite and becoming more apathetic. Your pet needs to be taken to the veterinarian immediately for a more accurate diagnosis with the clinical examination and start of treatment.