First of all, welcome to pets.ca but sorry to hear that you are going through a difficult time right now.
As far as some mental stimulation you could try feeding her meals in a Kong or other treat dispenser. Or hiding some treats around the house and getting her to find them. I'm sure some other members will be along soon to offer more suggestions.
I hope your girl has a speedy recovery and the biopsy is negative ....please keep us updated.