taga-saan ba yung mga parents? try to check sa mga kamag-anak. check to see yung mga lugar na napuntahan na nung bata from both sides. likewise, make a list of close friends (from the school and from the outside) and do visit them. don't just rely on making calls to the kids themselves. there is a possibility that the kid is there but when you do call them, they'd say he is not there.
you mentioned hypermart damsa, what is the story there? someone was with him there or someone just saw him there? do you know the time frame of when he was inside the store? have you asked the security of hypermart for info? how about asking them to review their "tapes" so as to gather more info.
likewise, seeing that the kid is "singkit" is there a possibility of a kidnap-for-ransom (KFR) scenario?
two step approach actually - think that there is a possibility that this is a "staged disappearance" and the other is that there is "foul play" or that he "disappeared" because someone wanted him to. having said that follow the lead on which you think is the most likely scenario without "neglecting" the other scenario. camp vicente lim in laguna will be a better place to ask for help given the number of days that he is already missing. likewise, going regional will give you more coverage, assuming that he is still in the area. if not, maybe someone in CALABARZON knows something and going regional will be a wise idea.
i've already asked a "favor" from someone recently, however i'd try to send word about this case now. good luck and lets pray for the best for this kid.