Why does popping this zit/lesion make me feel physically ill?

I occasionally get these odd spider bite looking lesions on my body. In the past, I've had one on my inner thigh twice, one on the back of my thigh, one on my arm and now I currently have one right under my eyebrow hidden by the hairs. It's'quite sore and painful to touch, i wait until it's "ripe" to pop it and squeeze out any puss or blood. However, when I do this it makes me very physically nauseus. The pus or blood doesn't bother me. I'm okay with things like that, i really am. However, just the act of squeezing this out makes my stomach feel ill and my head gets really hot and dizzy. Does anyone know why?