Mental illness or neurological issues?

I have been depressed for the past 2 years after my 6 year long relationship ended (Severe depression... continuous panic attacks, suicidal thoughts) But my other major problem started 2 years before all this happened and has gotten worse with time. I am unable to concentrate on anything at all even if it is an exam that can decide my future.I wasn't like this,I was an above average student and in past there were times when I used to study for 24 to 36 hrs at one go. After some stress related health issues I was checked out by  endocrinologist and a cardiologist who concluded that I needed to loose lots of weight or I could die (they also suggested a psych consult).I was scared and motivated initially and stuck to a healthy diet for 10 days then I went back to normal.Though I try hard to concentrate on my health and career I just can't and also for the past 1 year I'm having hard time remembering names of people,places and spellings of easy words. From whom should I get help(near Hyd?)