Sorry, it's late and I feel quite emotional, so hope this makes sense.
I am expecting my second child, due in July. My son will be 12 in August. He had seemed very happy about the new baby, and even insisted on having a copy of the scan picture for himself. He has been quite negative about school since Christmas, and after he refused to put anything except minimal effort in to homework tonight, I had a go at him and got on to him about attitude a bit.
So, he went to bed, and I went in to say goodnight as usual, and he was crying, which is very, very unsual, and eventually he came out with stuff like he feels the new baby will replace him and I don't think he's good enough. 
I think I reassured him, and he seemed OK again, but I feel so worried and distressed now. I don't know where this all came from.