This is often due to constipation.
Hard stool is in the way, soft stool gets around it and there is constant pressure.
Urinary incontinence has many reason.
Lower spine issues can deaden nerve pathways, but usually not to cause this unless very severe and at the right levels.
I suggest the following
A. Evaluation by your medical doctor.
B. Evaluation by an MD specialist in physical medicine and rehabilitation.
Often both problems can be help with the correct physical therapies.
Particularly given the back problems, this doctor, who is a medical doctor specializing in structure, and often be of most help.
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