It is good that you are no longer using any drugs or alcohol, as any substance use or abuse can make it more difficult to diagnose any underlying mental health condition.
Agitation is a symptom that can occur with many different mental health conditions, including whether the mood is normal, decreased, or increased. Agitation with a normal mood is most often seen with anxiety. Agitation can also occur only when the mood is decreased or increased. Anger also can occur when the mood is normal, decreased, or increased.
I ask about the mood changes because that would be the one of the primary considerations to diagnose the type of mental health condition that may be present. Everybody has some minor changes in mood from day to day, and that is normal. When the mood is decreased beyond the normal variability, it is called depression, and when the mood is increased beyond the normal variability, it is called mania. While many people with depression will never have periods of mania, essentially everyone that has periods of mania will ultimately also have episodes of depression, so the mental health condition that causes mania is also called manic-depression disorder, or more properly now called bipolar disorder.
When you say that your mood changes, would you say that there are periods during which your mood is decreased or increased, or both? Or are you only referring to feeling agitated or angry?