Severe ocd and anxiety past month. Went to doctor and felt better when I came home, even w/o treatment (yet). Why? Maybe a placebo effect?

Anxiety. Seeing a health care professional and getting reassurance that you are ok can be very helpful. It can keep our mind from thinking about all sorts of negative possibilities. If you continue to have anxiety to the point that it causes discomfort or interferes w/your life please see a mental health pro such as a clinical psychologist. Peace and good health.