Oh (((hugs))) and thanks zissi
Looks like he may have a bit of an upset tummy, if the twins do too - otherwise I'd have thought teething, if it smells. Either way, he won't be getting too much milk, actually bf (not fb, as it keeps being autocorrected to, lol!) will be the best thing to settle his tummy, and if you think he's getting diarrhoea, don't worry about feeding too often until that settles down as he'll need the hydration.
That's hard about DH, but I understand what you're saying. If you're not sure that cutting down night feeds by settling in other ways would be right for you all as a family, then try Pantley's gentle removal plan, which I posted above. No experience personally, but it may be right for you, and if you'd like some btdt to hold your hand, I'll ask around
Naps look pretty good really, but as I said before if you can get him to bed a little earlier it may help him to catch up - I realise that it doesn't help when you try for a CN but he doesn't take it