headbanging is normal for males and the opening of the mouth is just your beardie cooling off it does not mean that the tank is to hot. It is all normal and healthy
Do you have more than one dragon housed together? It may be that they are reacting to each other, possibly negatively. Here's an article about head bobbing:
I just set Swordtail's timer for his bath and paused it so I could actually fill his soaking bowl up and he crawled over my phone and canceled the timer
Mirage came out of brumation on April 26. He was doing great. On May 2 he started acting funny. We just redid his tank, and he keeps going into one of his hides. He just lays there. He shows no intrest in food. HELP!