Bleeding at 14 weeks

Hello, my first time in here. I'm in London UK. I had some bleeding at 10.5 weeks from my V after I squeezed out a poo (sorry!!! Too much info) then nothing, it happened again at 13 weeks, but more like spotting then on and off spotting everytime I went to the loo. Again yesterday I had fresh blood after going to the loo in the morning and evening. 
I had a scan both times and everything was OK. I was given an Ante D injection as I have Rhesus Neg blood type. Now I am
Confused if I need another injection. The midwife said yea and the doctor said no!! Their information conflicts everytime!
The doctors don't seem to know why I am bleeding as the baby seems fine and moving loads. I don't have a low placenta and not in any pain, but I am worrying a bit. We had IVF. Not sure if this makes any difference?? 
Any advice would be amazing!