Ds2 is 3 weeks old, not a particularly content baby at the moment and very clingy, so quality time between me and ds1, 3.5, has not been plentiful of late. Ds1 is very affectionate towards his new brother, but his behaviour in other respects has taken a huge nosedive. He now hits and kicks DH on a regular basis despite this having been, til now, unheard of since the terrible twos. He has tantrums galore, does this awful whiney fake-crying thing for ridiculous reasons, and (most worryingly to me) has developed a compulsive habit of biting his lips, to the point that they are now raw and painful 
I hate to see him so affected, and would love to be able to give him my unlimited attention to reassure him, but this is not an option with ds2 constantly stuck to me. Am considering switching to formula-feeding the baby so as to give ds1 more of my time…
Has anyone else experienced similar? How did you get through it, and are things ok now? I know a certain amount of playing up is to be expected with a huge change like this, but wasn't expecting it to be on this level. Am finding it pretty upsetting and I miss my previously-bright and cheerful little boy.