Jay,
I felt like suing for years after my first mishap with chemo in 2009, which severely debilitated me, but the ailments, hospitalization, and continuous treatments kept me busy! Looking into the matter, much wasn’t on my side, and may prove to be a waste of time and energy, other than trying to get better! I think there may be a certain time limit to take action too.
There is also more than one way to treat someone, as long as it’s not negligent, in my opinion. Most follow NCCN guidelines as a suggestion, but there are others too, from surgical societies to radiation oncology societies, that offer suggested guidelines too, and others.
I don’t fully know the situation, but you can go to three different doctors, I have, and get three different answers.
I wish you the best, and a speedy recovery!