Are the two rims the same diameter & ERD?
If you bent the rim when you were "bumped", then your spoke tension could be all over the cart trying to bring the rim back true. If you're been tinkering on the wheel for a while, then you'll probably know. But, if the wheel seems round and flat when you take it apart, then I'd just rebuild it. If it is not flat, then replace the rim.
I've wondered if mixing brands/materials of spokes is a bad idea as each will stretch a little bit differently.
Are all of your broken spokes related? For example outbound DS spokes?
In that case, if you've started with 36 spokes / 4 = 9 outbound DS spokes.
You've replaced 4, so you would have 5 left
