Carmen - has your Dr. checked for RSD (reflex sympathetic dystrophy)..  I went through at least 4 Drs. with symptons similar to yours (especially the discoloring and swelling) before a radiologist found it.  Mine came from out of the blue - no warning at all and at times is fine and other times I am in agony with intense burning as well as swelling.  Just a thought as I had never heard of it before.