What Causes Rapid Heart Rate With Hot Flushes?

My 24 yo son is experiencing rapid heartbeat, he feels like his skin is burning but no fever, and is very agitated. Also difficulty sleeping. Laying down is worse. This has been going on about 3 weeks. The last 5 days he was showing signs of improvement, almost normal, but yesterday his symptoms started coming back. He keeps saying he feels like he s going to die. Recent blood work shows testosterone level at 51 and estrogen level was told by dr that it was almost 0 (don t know the exact number). THS was normal. Before blood work came back he went to 4 different emergency rooms, had ekg that was normal. All told him severe anxiety. They keep giving him anxiety medication which seems to make him worse. I think something else is wrong and so does my son. I m 3 states away so can t go with him to the hospital. Not sure if testosterone being low would cause the symptoms he is experiencing or if something else is going. Could it be his thyroid even throw THS is normal. At al loss.