Not all blood work has to be centered, but if there are certain levels that seem to come back more toward the high and/or low of normal can indicate a problem. However, I don't know what all blood work was done etc. (so that is something you should check on next time you talk with your doctor)
I listed the side effect for the medication, which I also stated is "rare" but it's still a side effect and you didn't mention how long you were on this medication. starting after 2 years, probably not the cause. But sometimes our bodies can become immune to the medication, and if the medication is working properly, then probably not the cause.
As far as listing the lab results you indicated above, each lab has their own values. However to go by a standard guide line won't 100% accurate on this end. Click here for one explanation regarding TSH for example. That's why I say following up with an endocrinologist is generally best. But with this not occuring every night, it may just be your body temp is rising, especially since it also occurs sleeping in the chair. I don't know your room temperature both while in the chair and in the bed.
You may also want to see if it's something that you eat that may trigger this to occur as well. As certain foods, spices etc could cause this, especially for head sweating.
With it occuring in bed, it may be the pillow vs being a medical situation. So I would still suggest trying a new pillow. I know some of the better pillows are at JC Penney's and they do run some pretty good sales as well. There is on kind sold at Walmart, it's the memory foam and one side is similar to the egg carton, which allows airflow to keep the head area cooler. So for 10.00 to 15.00 may be worth trying.