I started bleeding between periods after kundalini yoga class. Is it possible that kundalini yoga is shifting energy in my 2nd chakra? Every time I go to kundalini yoga class I bleed after that.
That can happen when kundalini energy picks up all of a sudden. My impression is that the menstrual cycle in yoginis can work a bit like a safety valve - if there is more energy in the system then can be integrated, the body dumps it on various functions - the menstrual cycle is one and you can get more frequent or heavier periods for a while. It can be dumped in other places e.g. the digestive fire can intensify beyond what is necessary to digests your food and that can be the source of some discomfort.
You need to be careful with your self-pacing. Kundalini Yoga does use some very strong practices. Since you've come to this website, I will recommend that you read the AYP lessons on self-pacing. You can find them on the Topic Index page under the first heading "Advanced Yoga Practices (main techniques)"
And bear in mind Charliedog's advice too - if there is any chance it might be a medical issue, do check with your doctor.