PIP

I am 64 years old and am on high rate DLA for mobility and mid rate for care, (following an industrial chemical incident in 2006 in which I was told I would never work again following two company medical assessments) . I also had medical assessments for incapacity benefit and DLA, Incapacity beniefit stopped when I had enough Nat ins stamps, and after two years on DLA., they then put me on both mobility and care indefinitely. I have been worryingly waiting to be called for a PIP assessment for such a long time now that it is affecting my health. Any advice on what I can do or do I just have to keep on waiting and worrying.
Leslie