If you have a swollen lymph node, and based on some of the symptoms you are having, I would have the lymph node ruled out for cancer. He is recommending you see a haematologist because lymphoma is a type of blood cancer that effects your lymphocytes. It can occur in the marrow of bones as well as the central nervous system.
I am surprised that your CBC is normal with all of your symptoms. Do you have access to your blood tests? There are usually signs that would point towards cancer in your Whtie blood cell counts, specifically your monocytes and your lymphocytes, however, other things can also effect those numbers.
What does your diet look like? I would avoid any greasy foods, as they cause infamatory responses in the body and effect some more so than others. Avoid sugars, drink lots of water. Antibiotics can also cause a lot of symptoms as well, so it is important to make sure you are also taking probiotics to help keep a healthy balance with the flora in your gut.
I had lymphoma and I was a-symptomatic. So I really had to push my doctor to get the test I needed to confirm if my swollen lymph node (the only symptom I had) checked for cancer. My blood work was normal, everything was normal except for the node.
If you are having night sweats, and constant fatigue, along with a swollen lymph node, I highly recommend that you take the advice of your doctor and see a haematologist.
I also want to let you know that when I had the ultra sound of my lymph node done, the report concluded that I had a cyst and that my lymph nodes were normal. Doctors do make mistakes, it is your life, your body, and you really want to make sure that you are safe rather than sorry.
I look forward to hearing you successfully winning the battle against these symptoms. :)
You could spend months learning about CFS, and about gut dysbiosis caused by lots of antibiotics.
Consider that if you rounded up the top 5 CFS experts in the world, you'd discover that each has their own theory about what CFS is. No one really knows. But it does exist.