Hello,
If I'm reading this right, you're having trouble with over-tiredness due to a couple of bad nights?
Firstly you need to sort out what's happening at night - do you know, or has it just come out of the blue?
Secondly in the day, you need to worry less about the times, and put him down for naps as soon as he's giving you the signs - if he's overtired he needs to catch up. Don't, however, go overboard on the amount of naps he gets, as that'll then affect the night. So I think your instincts are right that the A time needs to be shorter. This is only for the next couple of days or so, though, to get him back on track again.
Can you give us a bit more information please? Such as his routine, is there anything medical upsetting him, what's your wind-down, is he swaddled, etc?