Collect 25 Serpent's Scale.
I see you have gained your own hatchling, <race>.
Have you been feeding it, cleaning after it, and playing with it properly? Only by doing so will it become strong and healthy.
Now let me tell you a trainer's secret. To the north, in The Widow's Wail, you can find a mushroom known as Serpent's Scale.
It is difficult to acquire, but this mushroom has powerful properties and important nutrients. Your serpent won't like eating it, but who likes eating their vegetables?