You definitely need to see a therapist and perhaps even be on medication. My therapist whom I saw for some time made me also go on medication because he said I had a severe case of clinical depression (major depressive disorder) so that's what I did, and I'm still on medication today, years later. It keeps me on an even keel so I don't drop into those awful lows or go into the highs either.
Perhaps this is what you need too, but first you need to see a therapist. Your doctor can refer you to a good one. So see your doctor and see what he has to say.
I wish you all the best. Let us know what he says, okay? God bless and take care. Hugs, Lee