Everyone has bad days, but when yours start to negatively affect your relationships it may be a sign of bipolar disorder. I can be irritated for no apparent reason for days at a time and this is often a symptom of mixed mania for me where I am hypomanic and depressed at the same time. My baseline is low depression so when I get a burst of creativity or energy that I have trouble acting on I get irritable quickly.

If this happens to you, learning mindfulness and anger management techniques might be helpful. It also might be a good idea to discuss it with your doctor.