I'm not a doctor, but I have a hard time believing that a sedentary lifestyle would lead to weakened pelvic floor muscles, unless you were so sedentary that you were wetting and messing yourself before you became incontinent. From what I've read things that do weaken those muscles include: pregnancy and childbirth, obesity, high impact exercise, chronic coughing, straining while on the toilet, heavy lifting, and getting older. Now, a sedentary lifestyle may lead to obesity and possibly to straining while on the toilet, so I'm not utterly discounting what you're saying. Either way, your plan to see a doctor is the right one.