Starting Immunotherapy for Stage 4 Metastatic Melanoma

Shocker! Someone told me how I might die and told me I have incurable cancer..I don’t believe that.
My journey started in a different state and hospital. They said I had squamous cell carcinoma, but it turns out after the pathologist here at Mayo look at the slides. It was melanoma. I came to Mayo because I needed some hearing aids at age 55. And the ENT said you have a tumor on your neck and I thought it was the scar tissue from the squamous which was really melanoma. And after various visits to the hospital for testing, they told me I have stage four cancer. Nothing‘s really changed in my mind from before I was diagnosed to the day after. We all gotta die soon sooner or later. And honestly, I know where I’m going.. I started a fast and have been praying for about 17 days just water and I feel great. I went to the beach today with my kids played football and enjoyed the day and I have more energy and I’ve lost a lot of weight. I feel like I’m at fighting weight right now. And frankly that’s my goal. I’m looking at this as a 12 round fight against Mike Tyson and I’m getting down to fighting weight. I’m building up community praying and pressing into God‘s Word. Honestly, I feel anything is possible. My body can generate millions of white blood cells and T cells and stem cells and can attack this “bad actor”. My body can cooperate with immunotherapy and so on. I guess I’m optimistic and new to this. And I have four kids and a wife, And so I will fight harder than I’ve ever fought anything before. I guess my question is what to expect with immunotherapy? What kind of side effects can I expect? My oncologist said there was some pretty high risk percentages in the neighborhood of 20% to other organs and such. Feels kinda high to me. I have a lot of confidence and strength, life and faith and I have no fear to be honest… I know how serious this is… Thanks for any feedback you can provide. Alex.