Competent medical opinion:

BVA Citation Nr: 0701681

Competent medical evidence means evidence provided by a 
person who is qualified by education, training, or experience 
to offer medical diagnoses, statements, or opinions. 
38 C.F.R. § 3.159(a)(1) (2004).
 
An opinion by a layman on a question of medical diagnosis or 
medical causation lacks probative value. Espiritu v. 
Derwinski, 2 Vet. App. 492, 494-95 (1992).