Oh Natty, how horrible for you. I went in at 23 weeks in terrible pain in my back, had scans on kidneys loads of test... turned out it was a prolapsed disc in between my L4-5 vertebrae , which i'd had nearly 2 years before. Unfortunately it got worse for me and i ended up on morphine... I ALSO had pain in my groin, which i was told was referred from my back as NOTHING turnued up on tests
the thing about pregnancy is, that, it masks all kinds of 'normal' symptoms associated with problems you may already have. i.e. I had had this back pain before but was TOTALLY different this time... Many of the midwives told me this, and 3 different consultants too. Being pregnant makes diagnostics REALLY difficult.
I know this is probably OF NO USE to you at all, and i'm rambling What i'm trying to say is , it may well still be the IBS. Its just you are experiencing it differently as you are PG. ? Dont forget, your bowl gets moved fairly significantly up into a different position as your baby grows, so perhaps this is why your symptoms differ...
Do hope you get some relief from it. oyu may find as your baby carries on growing and changing position, the pain eases a little.
Incidentally, i had to deliver early due to my problems, things improved for about 2 months post natally, then it all happened again, and boy did it feel like it used to. I'm still having terrible terrible problems with it. I'm only telling you this, as it confirmed the prolapsed disc again really.
Truly hope it improves. I'm a GI nurse, so really understand whats going on for you. Can you start some steroids at all?