Constitutional Remedy for Feline

Hello All, I am hoping you can help. My family just recently adopted a new kitty and I need help determining his constitutional remedy.

He is a male tuxedo cat, with some Bombay in him. Very lively, curious, and inquisitive - he has a need to check out and smell everything new that comes into the house. He plays a lot, like a kitten, even though he is five years old. He is social and follows my wife and I around the house and he sleeps on the bed with us. He is scared of thunder and rain and hides when new people come over. He is tall, long legs, and thin, but not too thin. He does get irritated sometimes and will nip my hand if I pet him too much while he is in my lap. He doesn't lay in the sun (our last kitty always found the spot of sun and laid in it) and he seems to run warm. He drinks a decent amount of water. He vomits occasionally and he has dry, hard stools and tends towards constipation (we are in the process of changing his diet from the dry kibble the shelter gave him, so hopefully that will help), but he is not open to this change! We have tried Nux and Sulphur for the constipation, but did not help. He twitches and jerks when he lies down on the bed at night to go to sleep and he seems to yawn a lot.

He had tons of vaccines and flea medicines at the shelter, so we gave him Thuya 30c when we got him home...that did seem to help and the twitching and jerking subsided about 50%.

I am new to homeopathy and would like some help in determining his constitutional remedy. Someone suggested Phosphorus to me...but I don't know enough to be sure.

Thank you kindly,