I’m sorry none of us saw this the day you posted. The forum is usually very good at listing new posts and many of us check at least once a day.
I’m guessing your lamb will have passed by now. It sounds like he had a rough time in the womb. There are often problems with triplets - they all try to get born at once, get muddled and stuck, one gets stressed and weak, then it blocks the birth canal, etc.
It’s so hard when you’ve worked hard to resuscitate them, but sometimes, between stress in the womb, birth trauma and delayed first feed, it’s for the best if they just slip away.