@astaingegerdm I too had damage to my anal sphincter during childbirth, I ripped all the way through it. It has been suggested that is the cause of my problem. I went to a urogynecologist for my urinary incontinence and also brought up the fecal incontinence. It seems implausible that what happened so long ago would take this long to affect me but she and the special physical therapist I went to both thought that was the probable cause. Reading that you say yours is getting weaker makes me realize that may be why I haven't had a problem up until the last couple of years. Initially the problem presented itself because I was having diarrhea. It turned out that my immunosuppressants had triggered lactose intolerance. I am not having that problem anymore but when active/exercising sometimes small solid feces will leak out.
The urogynecologist I went to told me about a surgeon at a different hospital who has had great success repairing this problem. I am considering going to him after things loosen up a bit. I was very involved in water exercise but right now I am thinking I may not be able to do that anymore.