I have Raynaud's phenomenon/disease. Self diagnosed of course.
I can say I am 99% sure that is what I have. The reason I'm so sure is because my grandmother has it and it is hereditary often skipping generations. My sister has the same thing, I think she was diagnosed with it though and has a worse case with it than I.
What is Raynaud's you ask? It is is a vasospastic disorder causing discoloration of the fingers, toes, and occasionally other extremities. Here is a picture of my Raynaud's acting up. It is the toe next to my big toe (is that called your pointer toe?). I can tell without looking that it is happening because it feels like the tip of my toe is a rock. Not heavy, hurting or unresponsive. I can still move it around as normal and walk like normal.
Looking at Wikipedia it tells me that I should avoid caffeine as general care. Just one more reason I should quit drinking coke...