fear

My 7 yo DS is very fearful of the dark, fearful of going upstairs by himself (even in broad daylight). He wants our dog in his room when he sleeps or goes upstairs to take something to his room or the hamper. I try not to be impatient, but this is not getting better. He is unable to explain what he is fearful of. We have tried appeasing him, reassuring him, etc. He was adopted by us at 8 mos of age. There has been no change in housing or family status. THis has been ongoing for several years. Help!Wondering if we need to consult a psychologist?