I am sorry to hear you are worried about your Lab. My name is Rebecca. I am a veterinarian and will do my best to help.
How long has she not been eating? I always take loss of appetite very seriously especially in older dogs. Not eating is often the only clue a dog will send us that they are sick or in pain.
What bathroom control problems is she having? Both urine, and feces?
If you check her gums, are they pink in color? If they appear pale, I am even more concerned about her. Can you take her temperature with a thermometer?
If she were my own dog, I would begin with a thorough physical exam: palpate internal organs and lymph nodes, listen with a stethoscope, take her temp, etc. Basic blood tests would also be a good idea, if not recently done, to check her blood counts, liver and kidney function, blood sugar, etc.
Let me know if you can get her temp, if her gums are pink or pale, and if she is having fecal or urine (or both) control problems.