Like others have mentioned, this can be pretty common for zyprexa side effects as well as depression. How long have you been on the zyprexa and have you had any recent dose changes? Do you have any depression specific symptoms (this varies from person to person but I know if I'm feeling irritable even if I'm not tired or have negative thinking beyond not having energy it's depression)?
Symbyax like someone else mentioned might be a good option unless you've tried fluoxetine and had a bad reaction to it previously