I have had two children by c section. Since I had my daughter 12 months ago, using tampons or trying to have sex is extremely painful. Any ideas why?

Post C/s painful sex. There are many reasons for post C/section painful sex or tampon placement. the most common is low estrogen levels if your are breastfeeding. The more complex is vaginal shortening surgically at the time of the C/sections. However, that problem seems unlikely as you are also having trouble inserting a tampon. See your OB MD for an exam to find out why.