I'm so sorry to read about your loss. It does hit hard, especially when they are so young.
Years ago I bought one back from a pet shop, only to find it was dead. They hit the poor thing with the edge of a net when they were trying to catch him. I didn't have the heart to take the body back to the shop, as I wanted to give him a proper burial.
I hope you persevere with another chipmunk, as when things go well they do live long happy lives, stick with it.