Hi everyone!! I am so sorry I took so long to post an update - this whole thing has been an emotional whirlwind for me.
I still have no answer as to the cause of his problems. Oakhurst says his heels got too low, which constricted his blood flow and stopped growth of the foot and caused deterioration of the sole. However, his venogram came back completely normal and they think there is no sign of laminitis. My farrier and several other vets I have consulted with vehemently disagree with this diagnoses. All his blood work came back normal, as well. I am waiting for an answer from Dr Huber (equine podiatrist) at OSU at this time.
Until then, we have put him in an Ultimate Shoe to raise his heels and increase circulation in the foot to promote growth, as well as 8 weeks complete stall rest (no handwalking). We are still treating for laminitis as well. His feet have also been treated as an open wound, so sanitation is a priority. I have him on aspirin. He appears to be in pain but in good spirits! I will update further as I get more information.