By the time you noticed symptoms, but did not have corid available, there is probably not anything else you could have done.
If you had been able to start them all on corid when Doodle showed symptoms, it might have made a difference for this chick.
For the future, you might want to keep corid...
Here's one way to get a weight estimate with no scale:
Find something in the house that has a weight on it--maybe a can of food.
Hold the can, then the chick, then the can.
Think about whether they weigh the same, or which one is heavier.
If the chick is a lot different than the can of food...