Mo
You say that you were receiving DLA Medium Rate Care and that the PIP "to remain the same", do you mean that you have received a Standard rate Daily Living award?
If this is the case then your husband would still be entitled to claim Carers Allowance, it is likely that the original CA claim was made against your DLA and that is why it has been refused either the computer of the administrator who dealt with the claim did not check whether there was now a PIP claim in award.
I'm afraid your husband needs to contact the DWP again to resolve the matter.
Gordon
Nothing on this board constitutes legal advice - always consult a professional about specific problems 
