For now, just help Diddy to settle down and feel safe again. Give him extra love and a treat.
Have you ever thought of grooming him yourself? Maybe your vet could at least show you how to trim nails.
Your poor little boy... I'm sorry he had such a bad experience.
If there is a supervisor or boss where you go, I would talk to them or write a letter. Letting a dog sit and bleed is totally unacceptable.
