Is this retaliation, nerves or paranoia, wrongful termination because I discovered too much?

I was hired to assess and manage the accounting department. I was fired right after my third week. I know Texas is an at will state and they can fire for no reason but I'm pretty sure that if someone is fired that they should at least be fired by someone that works there and NOT the new COO's sister who flew in from Minnesota. She is NOT an employee of the company. It seemed that once I actually started finding all of the wrong doing that was going on and the fact that I told them that you just can't start your company accounting books over just because they are so messed up. I discovered and questioned a lot but I thought that's what they wanted. This aside. I know that if someone is let go that you must pay the employee their last check by the 6th calendar day. I was told I would have my final check by direct deposit by Friday. I have not seen my money. I have a lot of knowledge in a short time so I don't know if that's what it is. Everything I got from them as far as feedback was all positive so the very abrupt dismissal is very confusing and unjust. I know there are laws broken and I'm tired of letting employers walk all over me.