abdominal pain and can't feel her movements 29 weeks +3

Laura • 37 year old mom of 3! 17, 14 and 4! Still TTC no.4 🙃live in Tamworth, 🇬🇧
So as of yesterday afternoon I have had horrendous lower andominal pain. It's there  constantly with a dull ache. My baby is moving but I can not feel a thing which is 100% unusual as I know her movements like clockwork. 
So I've been to be checked over - monitors are picking up heart rate and movements. Cervix is closed but very mucusy. I'm not constipated, no trapped wind either. No water infection. 
Next they measured and both midwives and the doctor got the same measurement but totally different to my measurement with my midwife last week. 
I was sent for a scan which confirmed their suspicions, my little girl isn't on the chart and is small 😔but everything is functioning fine. 
They are having me back in tomorrow for more monitoring and to try and find out why I can't feel her and what the pain is. 
Has anyone else experienced anything similar? Advise is welcomed! 
I've not overdone it either as I'm very very conscious as this is our third time lucky rainbow miracle 😇