Suggest Treatment For Sore Throat And Fatigue
Infectious disease/immunologist
Detailed Answer:
Hello and welcome,
This sounds like a difficult situation.
I imagine your son's doctor did a mono spot for Mono. But did he or she test him for antibody tests for mono? Mono IgG shows past infection and recovery, but IgM shows current infection. This may provide more information than the mono spot, if the doctor hasn't done so already.
While testing for this, also test for cytomegalo virus (CMV) which can present like mono.
I would also suggest a CBC with complete, manual, peripheral smear.
I think it would be good to do an initial work up for autoimmune disorders, including a sedimentation rate (shows if there is inflammation), ANA and rheumatoid factor to start with.
Also test his thyroid function: TSH and free T3 and T 4.
I was surprised to see that he was on steroid. If they were oral and for more than a week or two, this will knock down the immune system afterwards and can cause people to have the symptoms you described.
If you feel you have come to the end of what his own doctor can look into, I'd suggest and infectious disease/immunologist. Best place would be your nearest university hospital or major medical center.
I hope this information helps.
Yes, a thyroid problem is possible
Detailed Answer:
In teens, it's possible to get a viral thyroiditis which can create a state of hypothyroidism and fatigue and can resolve slowly. That's why I listed the thyroid function tests (above). Antithyroid antibody test could be included in that thyroid panel too.