If the "blahs" are interfering with your normal everyday life, and it's been going on for more than 2 weeks, it's time to see a doctor. For instance, if you don't want to do anything, go anywhere, take care of yourself, do the house work, go to work, etc., then it's time to get some help.
Your doctor should make sure that you're ok physically, and if so then he should refer you to a therapist. OR he could possibly put you on an antidepressant. But he should do something!
So keep us posted on what happens, ok? We'd sure like to know! God bless and take care. Hugs, Lee