welcome to YT and i wish you and kiya the best of luck in your new move & journey!
i am not sure about the cold vs allergy question but for the teeth brushing, just find a
pet toothpaste that she likes the taste of...do not push it right away - just let her lick the toothpaste off the toothbrush...let her get used to your putting your fingers (or the toothbrush if she does not seem to mind it

) in her mouth and touching her teeth and gums ... then try to brush a bit, try to brush longer the next time, etc...i am no expert but this has helped with my babies!
mine are still squirmy when i brush their teeth but you just have to be persistent

they will eventually learn (i hope! lol) that you are going to win and they WILL get their teeth brushed
good luck and post any questions you might have! welcome again!