I've noticed with my beardie that the tip of his tail will change colors and get darker like his back and tummy when he's upset or basking and trying to get warm. So I'd say it's just that.
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!