3 week old won't go to sleep in cot

[LilJ]

My DS who is just over 3 weeks old has been sleeping in his cot almost since birth, but in the last 4-5 days he fusses and cries every time we put him down in the cot to sleep - if he's already asleep when we put him down he tends to wake up shortly afterwards and starts to flail his arms around and make noise. Last night we put him in the pram and he fell asleep almost immediately after being put down - so we think that maybe he doesn't like that the cot is so big. Is there something we can put around him that will make him feel more secure in the cot? We've tried swaddling him but he doesn't like that at all.

he's lonely, methinks. tried a moses basket?

i co sleep w/dd2, but it's not for everyone.

she can't sleep w/o me near her.

swaddling is a funny thing. Babies seem to really struggle while you do it, but it helps them settle in the end. It is really important to get the swaddle tight as if their arms get out, it makes it worse. Here is a great link to how to swaddle effectively. I swore by it when mine were little.
swaddling

Roll up 2 large towels and place under the sheet so baby has a 'trough' to lay in with a barrier either side so feels more contained.

Do as Matnanplus suggests, but also take the shirt that you have been wearing all day, wrap it round a smaller rolled-up towel and lay it on top of the sheet in a U-shape so that his head is inside the U. That way he will be comforted by your smell, whichever way his head turns.

Babies instinctively push themselves upwards, seekign pressure on the top of their heads. My two could move all the way up the cot at this age, but putting something across the cot for their head to press into stopped them. The rolled-up shirt serves this purpose too.