I want to know if there's a way to sue Walmart for the money I lost out on and for making me look bad at other jobs

You have no claim against Walmart for terminating your employment with Walmart. Walmart can terminate your employment for any reason (aside from discrimination based on a protected class). You might have a claim for defamation (not "defecation" which is something else entirely) if you can prove that Walmart employees made maliciously false statements and that those statements cost you specific jobs. However, such claims are usually very expensive to successful pursue so you will want to balance the damages you think you can prove against the expense to determine how you want to proceed.

You can generally be fired for any reason or no reason at all.