I have large pimple like bumps that only appear in my stretch marks. They only started happening after I was put on birth control after my pregnancy. They are bigger than pimples but never come to a head and only leak clear liquid when popped. It takes several weeks for them to go away after being popped. When you first pop them they leak clear fluid and then scab over and then the middle sinks in like a crater or something and they come back a few weeks later.