How to link Question node to current page?
Make sure your Question-content type as a field called "node_reference_field" with the EntityReference module. 

Once that's done, you just need to make sure the nid of the current node is stored in this field. Since you're using a custom block with a generated form, it won't be that hard.
I suggest you try something like:

$node = node_load ($form_state['nid']);
$form['node_reference_field']['value'] = $node-&gt;nid;


I'm not sure about the coding, but with the EntityReference module, you aren't far from a solution.