If I am understanding correctly, there isn't a relationship between the walks you take in the mornings and the headaches you experience in the afternoon. I don't really have sufficient information about the nature of your headache to reach any firm conclusions. Your blood pressure though a little on the higher side, is not inordinately high; furthermore your cholesterol level is not responsible for your headache. I would suggest you consult a neurologist; make sure you give them a detailed account of your symptoms. They will be able to perform an examination, order any tests that might be appropriate, and thereafter give you an answer as to the cause of your headache.