It is absolutely not silly to be this worried - he is your child and you have every right to be so concerned about him. It sounds like you are doing everything you can for him right now, and you'll be taking him back to the vet tomorrow to get re-checked - keep breathing and try not to stress too much. I know that with my kitty-girl Diana, if I am stressed out, she knows that I am stressed out and she reacts accordingly.

All good thoughts and prayers heading to you and to Max.