itching

For the past couple of years I have been experiencing a terrible itching on my upper arms with no apparent rash.  I have been to a dermatologist 3 times and they have no explanation.  They have given me different creams that do nothing.  When I had my lung removed last year I was unable to take any of my vitamins simply because I did not feel like it.  I noticed that the itching went away.  I am now going through it again.  I thought that I had eliminated the source last year but apparently not.  I take B6 100mg, E 400mg, gelatin, calcium 500mg, fosamax 70mg with D, Thyroid meds .125mg, naprosyn 500mg, zyrtec 5mg, evening primrose. Could it possibly be the vitamin D in the fosamax?  If not could it be any of the other vitamins that I am taking?  Are there vitamins that can cause itching?  This itching is also mixed with a burning sensation.  I am almost out of my mind with it.  Once I start itching I can't stop.  It just gets worse and worse.  Is one of these supplements causing the itching?