I hope this helps some of you as I recently had this and read about a cure someone had found.  

2 things to do, first, go and get Head and Shoulders clinical strength shampoo (if you can't find this just google what the main active ingredient in it is and find another soap with it in there).  Rub this all of the effected areas about 10 minutes before a shower to your dry body.  Then take a shower and use this on your head as well.  Do this at least 3-4 times then you can start just using it in the shower.

Second, go tanning or lay out in the sun.  I only did this for maybe an hour total for a couple days.  The combination of sun and this shampoo took care of my Pityriasis Rosea in just 4-5 days after dealing with it for weeks.  It has also worked for many many other people who have tried this and reported back.

Hope this helps.