Anyone can sue anyone for anything in America. All it takes is plenty of time and money and heartache. Walgreens will just look at this as a nuisance suit and put you or your attorney up against one of their junior litigators and if they lose, will move up the legal food chain until you give up. You and your lawyer don’t want to give up? Figure on 10 years before all delays and appeals are heard.
I seriously doubt any lawyer will take this on contingency, unless they are right out of school and looking for experience. Even then you will need to pay all sorts of court filing and suit related fees.
Please move on and forget about this, the sooner the better for the sake of your health and sanity if nothing else. Nobody except even the lowest level employees in the Walgreens legal chain will probably even know about this if you proceed. They may even promote the guy you are less than content with.
I agree with Terry4, this is going to hurt you emotionally a lot more than anyone at Walgreens.
Just my opinion - I have no vested financial interest in Walgreens.