Help!!

Here's a puzzle, any suggestions please email me jesssoutar@hotmail.com.

Izzie is a very good sleeper.

Circumstance has meant that she has been sleeping in the port-a-cot and we can put her to bed and if she is tired she will roll over and go to sleep and if she's not she will play and giggle and coo for a bit then go to sleep.

But, when we put her in her actual cot - it is big and wooden and has a nice firm matress and cost a lot - she arches her back, goes bright red and screams like she's been stabbed, then coughs a lot, when we go to her and pick her up she calms right down, but the minute we put her back she screams again.

For some reason she will sleep anywhere (our bed, the port-a-cot, Bax' bed) but her own cot. And it's not just crying, it's a very strong reaction.

At the moment her bedroom has in it the port-a-cot and her proper cot but I won't use the proper one because she seems to hate it so much.

What should we do? Is it okay to have a baby sleeping in an Argos' port-a-cot permanently? Is her reaction fear, allergy, or something else? Do we give in and sell the real cot and matress?

Help!!!