SIGECAPS is an acronym taught in US medicine for the diagnosis of major depressive disorder: Sleep disturbance, Interest loss, Guilt, Energy loss, Concentration loss, Appetite changes, Psychomotor agitation, Suicidality. And must have Depressed mood or Anhedonia (inability to enjoy things previously enjoyable).
The history of the SIG E CAPS acronym is also interesting, I've heard it was short for SIG (old shorthand for "to be prescribed") Energy CAPsules.
I would say it's worth talking to a doctor about how you feel. There are many things that can help. If you are in the USA, if is likely that they will use the PHQ-9 form, so consider looking at that questionaire to see how it aligns with your mood. medcalc is a common site that many of the residents at my institution use for these questionaires and other various scoring systems.