I have a 2 year old Pitbull named Chloe. I put her in her cage for bed Sunday night and woke up to her whining. I got up to let her out to go potty and she had her leg up, not putting any weight down on it. I laid her down and squeezed all the parts of her leg and she cried when I squeezed her thigh, right above her knee.

All day, Monday, she didn't put any weight on her leg and just laid outside all day. Before bed, I had to go out, call her and weight for her to slowly limp to come inside. Usually, she'd want to come inside ASAP.

Now, Tuesday morning, she is still putting no weight on the leg.

In August 2011, she had her leg shattered, had surgery, and a external fixator (leg brace) in until January 2012. All that cost $3000 and I have no more money to put into her. Any advice helps.

Unfortunately we cannot diagnose her leg problem over the internet.
It could be as simple as a muscle strain or more serious things like bone or tendon injures.
What ever you do, please do not give her any medication meant for humans use, some pose very serious complications for dogs like liver/kidney damage, stomach ulcers etc.
Call your vet and have her checked if it continues.
An initial exam shouldn't break the bank, go from there and before any diagnostic testing is done (most likely x-rays) get the price before hand and see if they can work with you or can offer you other options.
Good Luck, I hope you get her sorted out.

Best advice as Lady Sam suggests. Make sure it is the vet who did the repair in the first place... no one knows more about what went on than the person that fixed it.