For the past month I've felt super irritable, and even depressed. Everything makes me mad. Why do you think this is?

Depression. Depression can lead to irritability, frustration, and mood instability even. Get it treated.
Possibly depression. If you can identify some events in your life that could've triggered these symptoms. Your reaction may be within normal limits. However, you may be having depression if you have lost interest in doing things, feeling depressed more than previously, sleeping too little or too much, feeling tired with little energy, poor concentration, poor appetite or overeating, or feeling bad about yourself.