I am sorry to hear you are worried about Kasey. I am a veterinarian, and will do my best to help.
I am also sorry an expert did not help you sooner. I just came online and saw your question.
If she were constipated, she might not be eating, and would probably be straining to defecate.
Pacing at night in older dogs can mean pain ( arthritis
, back pain), mental confusion (older dog can sometimes be restless at night just from brain
aging/arthritis, or have their sleep cycle become different), stress, anxiety. You could try melatonin at bedtime to try to help her sleep; it is a safe over the counter hormone and dog can take 3 to 6 milligrams.
You could try a baby aspirin, or prescription pain medication from your veterinarian at bedtime. If you try aspirin, give it with food, and do not repeat if she vomits. One baby aspirin or low dose aspirin per 15 to 20 pounds.
Having a good physical exam by your veterinarian if that has not been recently done, and asking about prescription pain medication like carprofen or meloxicam or tramadol might be a good place to begin.
Let me know what else I can help with or answer.