Hi Pip,
sorry to hear that you have this ache....a couple of posters here seem to have had it, too. Someone said( sorry I can't remember who it was now), but she had this ache for about 6 months and then it just went off.
The best thing is to have a word with your GP...she might book you in for an ultrasound scan....at least this will put your mind at rest....it might be your Ibs because of all the worry about your Mum, but it's really best for you to be checked out...just for your peace of mind....it really sounds like you have enough to cope with. Please be brave and see your GP.
xx