It burned as you regenerated. It always burned, though. Every time. During an adventure with the Master, you two got into a deadly situation, and now you’re regenerating. Finally, as the regeneration energy surrounding you dissipated, you looked down at your new hands, then up at your new hair. Still not ginger..

Before you knew it, you were passing out, then waking up in your bedroom in the TARDIS. You can hear the Master at your bedside.

“Go back to sleep, Doctor. You need to rest.”