I have ibs-c but wen i go toilet (usually once a week) i end up with tender bowels and oower back ache?

Probiotics: One of the most helpful things you can do when you have digestive issues such as IBS, is to get started on a good quality Probiotic. This helps but better balance between the good and bad bacteria in your diet. Try getting rid of Gluten as well. I have not had one person who has done so that has not felt immeasurably better as a result.