I am not sure if it's a burnout. I am perfectly sound physically. I had a small period of time when I couldn't think clear, it spanned 2-3 weeks though so may be can't call it small; I barely remember few memories of that time. But it was 3 months back and I snapped out of it as soon as I got physically well and was as productive as I am normally.

Now although I am physically sound, I am unable to concentrate. I can't focus for no apparent physical reason other than this feeling of too bored to live. May be I am actually depressed, and should go get some counselling.