Welcome to the site. Sorry that you had to find us all and I'm sorry to hear what you're going through. But you so did the right thing in coming here as you are definitely in the best place for support and help, and you'll get a ton of both from everyone here.
Not much I can add to what the others have already said to you, but I just wanted to welcome you here. Please do keep coming back and let us know how everything goes for you. And if we can help in any way just ask and we'll do what we can for you.
And for sure, certainly seeking these 2nd or 3rd opinions will not do any harm at all, so go for it! You mentioned photodynamic therapy at Mayo, my dad had that as his treatment here in Scotland so if I can help with that if you want more info on it please just ask. And please know as well that we are here for you, stay strong!
Any advice or comments I give are based on personal experiences and knowledge and are my opinions only, they are not to be substituted for professional medical advice. Please seek professional advice from a qualified doctor or medical professional.