Allan suffers from mild mood swings that range from dysphoria to hypomania. His mood can change rapidly and at times his behavior borders on eccentric, but he still holds down a job at the neighborhood hardware store. Allan is most likely suffering from

Cyclothymic disorder

Explanation:

Cyclothymic disorder, which can also be referred to as cyclothymia, is a relatively milder mood disorder when compared to bipolar disorder or major depressive disorder. It is characterized by several alternative short periods of depression and hypomania. In order words, the sufferer experiences emotional ups and downs often over time. However, it is not as severe as bipolar or major depressive disorder, as the individual can still function normal and carry out his normal daily activities.