Sounds like you're having a very rough time. Which test confirmed the liver spot, just out of curiousity?
I had biliary problems last summer, where I kept getting pain on my right side where my liver is located, along with nausea, chills, loss of appetite, diarrhea immediately after drinking alcohol, gaseousness, frequent urination, dark urine and bowel movements that ranged from pale to white to almost black. I had blood tests to check my liver function, a CT scan and an abdominal ultrasound, nothing came back positive for liver or gallbladder issues. The symptoms have either vanished since then. I never found out what it was.
I've had two CT scans myself. It's very important to be still and hold your breath when the technician says to. It may be difficult, especially if you experience an digestive reaction to the barium swallow like I did. The problem with CT scans is that they can show whether or not a mass, inflammation, fluid or other deformities exist. They need to get the best pictures they can, however they should have viewed the pictures before discharging so they could repeat the scan for better images.
The problem is that CT scans show that something abnormal is located in your body, but they cannot determine 100% what it is sometimes without a biopsy of the tissue. Many diseases or growths look similar to each other. A spot on the liver could be a cyst, it could be cancerous, or it could be from an infection or autoimmune disease.
The nuclear test shows much more detail of your liver than a CT scan or ultrasound. It sounds easier and less invasive than a liver biopsy, which is probably why he ordered it. If you are that concerned about your liver, you should take the test. It may hurt at first, but it's probably worth that temporary pain. He's probably just trying to do what he can to save you from surgery to get a biopsy, which would be much more risky and painful.
I had to make a similar decision involving a mass in my right lung. My pulmonologist thinks it's a fungal infection, but he can't know for sure. So I had a bronchoscopy done this morning and they had to put a tube down my lung and took a tissue sample while I was conscious and given very little medication for sedation and pain. It hardly helped with the pain and torture. But it may be worth the torture so I can know what it is and treat my chest symptoms.
I'd say take the test, you might not regret it.