Discomfort left pelvis area up along inside of ribs. feels full or tight. lower back discomfort. tingling above knee/bottom of big toe. if i lay butterfly position legs, pain between leg and pelvis. joint? all on left side. what could cause this?

Neurologist: Low back discomfort combined with tingling in one leg and foot raises suspicion of nerve root impingement by a bulging disc or spur in a lower spine vertebra but pelvis and rib involvement would not be explainable by that disc or spur. I would start with an examination by a neurologist. Appropriate testing will be done. You may then be referred to an orthopedic specialist if deemed advisable.