You mention the neighbor's wheat looks fine.   So that suggests to me that what you're seeing in your wheat is probably not "cold temperature" related.  

The wheat leaves in one of the photos do hint at there possibly being some disease.   If it was me, I would send some samples to a lab to determine if there is indeed some disease in the wheat.   That knowledge might not have much value for this current situation with your volunteer wheat.... but could be valuable knowledge for future wheat plantings.   Something to consider.


gordon