ESA 50 form, why now

Hi all, last week I received an ESA 50 form that I am supposed to fill in and I am at my wit's end. I have been on ESA for 12 years after having an accident while I was a self employed builder and after operations and every treatment under the sun I was told that I probably would have constant pain in my shoulder for the rest of my life, I then found I had fibromyalgia and then anxiety and depression were I tried to kill myself twice. I also have been getting pip enhanced and motility for the past 6 years and then this ESA 50 came through the door and I just can't understand why now and it has set me back years and back into the dark days of depression. Is this a regular thing or am I just paranoid