Any mummies encounter tailbone pain? This morning I woke up I felt pain in certain movements. Is it related to my prolong bad posture ?

Most likely it isn't due to bad posture, unless you are sitting right on your tailbone constantly. Tailbone pain, along with hip pain is very common due to pregnancy. Your baby is probably pushing on a nerve and causing pressure that is causing it. Heating pad with Tylenol will help relieve some of this pain. Good luck sweetie!