Nipple stimulation is no joke.... I was bouncing on my yoga ball and I only did each nipple for 15 minute and my back started to hurt so bad and I started having period like cramps.... I went to sit on the toilet because it felt like I had to go to the bathroom but nothing...I started to have tighting contractions that were very uncomfortable I could even get off the toilet I sat there for a good 30 minute and now everything has died down and I feel so much better .... I think it was working but now I'm to much of a punk to start back up again 😂