Looking for help, advice, or just reassurance

Hi, this is my first post and first visit to this site. I am desperate to get help for my son, he is 20 years old and up to a year ago he had the world at his feet. He has always been an anxious person but a year ago my husband passed away and this just seemed to send my son into a downwards spiral. He wont seek help and every time i talk to him about it he says he knows where to go to talk etc but just wont do it. He was once a happy vibrant and talented boy, who was and extremely talented dancer and was sought after by many european agencies. Now he spends all day just moving things around his room, he struggles to commit to things and he hurts himself. The slightest little thing will make him anxious and he speaks about how useless he is. He was being treated for anxiety at one point but took himself off the medication. He has self harmed himself several times and i am so scared he will end up a statistic. I just dont know what to do, where to turn or how to help.