Tiredness for reasons unknown

Patient: Why am I always so tired? I am 27 a healthy weight for my body. I take regular exercise. I eat a very healthy diet. I also take 20mg of cytalopram daily for anxiety though that is nothing new and I have been taking it for years.Recently I feel week as a lamb and all I want to do all day is go to bed. Previously I had been a heavy drinker but 3 weeks ago I gave it up entirely and although I have noticed improvements in my skin and emotional state the tiredness remains,actually could be said to have got worse. I dont think that it is an emotional or a symptom of depression,(tho given my history doctors keep telling me it is.I know myself well enough to know that this is not the case as there is a difference between lethargy and physical tiredness), my general state is very good and better than it has been for years. in fact the only downside to my life at the moment is this chronic lack of energy and tired and achy limbs.Any ideas?

Doctor: