No, what you have is not a serious crack, a serious crack would be 3/4 - an inch wide. take a deep breath and google some serious cracks.
It seems you already know what the possible cause is, you've had some serious structural work done and the house is settling around it. There are issues called shear cracks which can be a sign of movement in the house but you already have a good idea what might have happened. i.e. steel beam put in.
I could be wrong about how serious it may become without treatment but at the moment just put the bed back and call an estate agent. :)
No, what you have is not a serious crack, a serious crack would be 3/4 - an inch wide. take a deep breath and google some serious cracks.
It seems you already know what the possible cause is, you've had some serious structural work done and the house is settling around it. There are issues called shear cracks which can be a sign of movement in the house but you already have a good idea what might have happened. i.e. steel beam put in.
I could be wrong about how serious it may become without treatment but at the moment just put the bed back and call an estate agent. :)