When I am driving in d5 gear, d5 blinks continually.

You have 'fault(s) in the transmission , you should get the codes read (NOT at a parts store , that will not read trans codes in many cases. Go to someplace like AAMCO , better chance there! THEN post the code(s) here and I can fill you in on Honda suggestions(SAME trans.) Most of the time it's a clutch pressure switch , not to bad .