Done Surgery To Stretch Throat. Numbness In Body, Stomach Tightness, Cold Limbs, Weight Loss

in late February, my brother had surgery to stretch his throat. For the next 3 days, he experienced blood in his stools. Next he felt burning sensations throughout his entire body, proceeded by numbness and tingling in his feet and hands. Next came a cold and clamy feeling and tightness in his stomach. His feet and legs are always ice cold. These symptons occur 24/7. He has had blood work done, x-ray and MRI, which all came out negative. He was a very, very hard worker. He was a Mason Contractor. Every summer he made a big garden which he would tend to each and every day. He also walked 6 miles or so a day and did groceries,etc. Lately he has told me (sister) that he is giving up everything, he has no quality of life. He can't do anything anymore, like he use to. No more working, cooking, gardening, etc.nothing- He also lost over 40lbs. within a few months. I am so afraid of what might happen to him, cause he talks about ending it all, he can't go on like this any longer. I keep in touch with him each and everyday. He never, ever told me these things before and I never know from one day to the next if he'll tempt to do whatever to himself. He feels worthless. I try my best to make him laugh, and talk about the good times, but he seems far away.