Is My atiel Sick?

I got my very first atiel on February 6th (Superbowl Sunday) and usually he is very active and talkative but suddenly today after he made contact with my 2 Parakeets (Which are both healthy) he became super tired and now he's been sleeping almost all day on and off, he is also moving slower and is more defensive, he also has been sneezing more and when he does there's a noticeable mist. Could he be getting sick?