Hi everyone!
I experienced the same, woke up in the morning with stains in my right and left hand very similar to the ones you posted. Before this happened i washed my hairs with a caffeine shampoo and used an oil for my hair, i cooked an apricot jam cake that was Little burned and eated it and before a tomato sauce pasta, i did 2 showers washing 2 times my hairs, i smoked tabacco like usual, can t explain the reason. I read almost all your post but what could be the common pattern? I thought was nicotine related but It doesn t seem so... To sum up which are the common pattern a? Hugs from Europe!