Get another offer that lays more and use it to negotiate.

OP here. I really like my job and don't want to quit but I am underpaid already. Any other options??

Back on his word? Get use to it in business. He could have just as easily said, "circumstances have changed".

Look for another job. Unless you have it in writing, you can't do much else

Look for another job.

My boss said that he would give me a raise if we hired on another person but now that we have he refuses to do so. He told me that he would but now he is saying that he never said that. He is going back on his word. What should I do?