Could it be IBS?

Hi,
Looking for a little advice please. Sorry if TMI. Since I was about 6 months pregnant I've been feeling really awful when I have a bowel movement. I figured baby was sitting on something and asked my Obstetrician and Midwife but they had no clue. Thing is baby is now 6 months old and it's still happening. Not every time but maybe twice a week (I generally have a BM at least once a day) I get goosebumps, shivery, feel nauseous and sometimes get a sharp pain on the left side of my abdomen. BM is 'hot' feeling and generally quite firm and large (I eat a lot of veggies and fibre) to begin with then runny stuff. Waiting on a GI referral but the NHS taking it's sweet time... Does this sound like IBS? My sister has ulcerative colitis but I've never passed blood or mucous so didn't think it could be that.