underactive thyroid
"I have been taking Levothyroxine .88 MG for at least 5 years. Recently I have developed Sweating and being very tired. I was taking my pill during the night as you are supposed to take it on an empty stomach. I have recently discovered that taking it at that time has caused me to have pounding heart beats and fluttering in my chest. I went through a stress test only to realize it has been caused by my thyroid medication. I changed it to morning before breakfast and have found it to be better.  However I still get tired very easily."