Infection or white ink allergy?

I'm a beginner tattoo artist, currently practicing on my own legs. I did this tattoo 2 days ago. After finishing the black and blue parts of this tattoo I wanted to do some white fading from the edge to give it a more stoney feel. The effect you see appeared instantly. 2 days later it's still sore, sensitive and somewhat swollen. I'll also mention that I applied white ink on the entire area along the black outline, packing with a rounded magnum in circles, but the ink only shows in that lower part in a weird straight line.

I'm curious if I have a white allergy or if I f***ed up the hygiene protocol. Any ideas what it might be?