Headache and tiredness. Course to take?

Hello..Since last month, i have continous headache all through the day. Its very subtle and becomes irritating and noticable when i start teaching or travelling. If i travel even for half an hour, my head starts hurting like anything..specially area around my eyes and my forehead..i try to go for walk or exercise..but even if i walk a little, i start feeling breathless and my head hurts..i do not feel fresh anytime..i feel week, tired and my head throbs. I cant wake early..and i cant sleep early even if i try. I also forget a lot of things and stutter while teaching.i am on leviteracetam 1000 mg a day n take thyronorm 12.5 mg n multivit as prescribed by doctor. I want to ask that which speciality shall i consult with? I went to gen physician once, she referred me to cardiology..cardiologist said all tests are normal..pls help me as to which course to take?