I am not a doctor therefore disregard what I am about to say as nonsensical madness
A 5 point drop in blood sugar in 20 minutes after bolusing (1pm – 1:20pm) seems rather quick? Mine normally takes at least 20 minutes to start, let alone do something.
Is it possible that you bolused at lunch time (12pm) and it was simply that bolus that kicked in? In other words are you heading for a hypo?