Tristan keeps waking during the night screaming and NOTHING I do helps. Some nights I just put him in with us and he's asleep before I lay down next to him, others like tonight... DP and I are tag teaming holding him while he screams, coughs and almost chokes I don't know what's wrong

He's had a drink, has a clean nappy, appears to be otherwise well just screaming him head off

Any suggestions?