Hi Dancer and welcome!
I am sorry to hear of your related illness, symptoms and worries that has resulted from this ordeal. Being sick can definitely be a trigger for health anxiety...so know that you are not alone with this challenge.
If your doctor and tests have all assured you that you are healthy and not showing signs of the issues that you fear...
...then treating the anxiety as the root cause of this issue is going to be the next step that you want to take.
No doubt your doctor has told you that the Mono virus can linger for a long time in the body...and though you are feeling better overall, certain factors can threaten a relapse. It is for this reason that the lymph nodes can take time to return to normal size.
Like you said, stress...as well as fatigue may cause your symptoms to try and return...
...so getting as much rest as possible, as well as practicing self help techniques for anxiety management will help.
See the top of the main forum page here for our Resources. You'll find great material to get started with there.
If you find it helpful, keep us posted on how you are doing...we will do our best to keep you encouraged!
"Courage is not the abscence of fear, it is feeling afraid and doing it anyway!"
"Worrying does not empty tomorrow of its troubles...it empties today of its strength."
Corrie Ten Boom
Panic Syndrome recovery due to CBT