Constant moods and anxiety, any sign of a mental disorder?

All depends. All of us are moody and irritable at times. If moodiness persists and isn't clearly connected to things happening in your life, then it could be a sign of something worth looking into, especially if other symptoms such as tiredness, decreased motivation, poor sleep, or thoughts of self-harm are present. May be physical, may be psychological; whatever the reason don't hesitate to seek help..
Possibility. It might require mental health evaluation if the moodiness & anxiety interfere with day to day function. Moodiness sometimes signals depression or a bipolar disoder. High anxiety can be a marker of several types of anxiety syndromes. Ptsd or OCD & intermittent explosive disorder all share those symptoms as well. Medical illnesses have to be considered like thyroid, cardiac or hormonal problems.