Are there any other changes in his life style or health? Sometimes certain meds can depress scores. Others can help the scores a bit such as stims for an attention difficulty. Also, scores for younger kids are a bit less reliable than for older kids as they are still developing cognitively.
The pattern of relative strength has remained the same and this is an important piece of data. Did the same person administer the tests? Was it over one or two sessions? Was he feeling poorly during the first session?
It seems there must be some variable that contributed to the large difference.
