What Causes Bumps On The Back Of Lower Leg?

Hello, my name is kathy. I had bumps on the back of my lower leg, behind my knee and one on the l.side of my face infront of my ear and one on my right lower arm above my wrist. And several on my rightside of my neck and shoulder. The one on my leg i did myself. I popped it and almost as much as a marble in size came out white dryish puss. That went away. On my face same thing but it refills. Husband squeezes the ones on my neck, little puss comes out but it refills. What and why doc?