Hello, this is Kitt,
I have know idea re backpain and probiotics but your physician is the one you may want to talk to as he/she should know all the supplements you take.
I think you made a wise choice in stopping the Probiotic and now you should have your back pain and other sx evaluated by your physician..............perhaps you have a gall bladder issue. That is just my 2 cents worth. I am not a physician.
I had the exact same problem. I tried different brands of probiotics and they each have a different pain level, but they all start a few days after starting and end a few days after stopping. I also recently noticed that childrens gummy vitamins have the same results. I am IBS Celiac and not sure if that is related.