Fur loss can be related to a number of things: medical issue such as reaction to vaccination, HyperThyroidism etc, allergies to either an ingredient in food or something environmental ~ household cleaners etc, stress - new animal/person in the house; moving/vacation etc, fleas with or without an allergy to them.
I would say the first thing to rule out is medical issues, how old is Tucker? Bring him in for full blood panel & urinaylsis to check all levels & functions.
In the meantime you can check him over for fleas - part the fur near the back of his neck so you can see the skin, if you see small black things zipping around you've got fleas or if you see tiny black dots drop them onto a slightly damp paper towel & if is turns red thats' flea dirt aka dried blood poop. You can also put a dish of water with a little dishsoap on the floor of a room you cat frequents, turn a light on near the dish & close the door so Tucker doesn't have access to the soapy water. If you have fleas they most likely will jump in & can't jump back out because of the soap
Avoid biting when a simple growl will do
The Spirit Lives As Long As Someone Who Lives Remembers You - Navaho Saying
Vindication ~ For all those pets who became sick or lost their lives from tainted pet food