Correct, the shoes just masked the lameness. The current issue with him being worse could be a bruise, but it may not be. Taking the shoes off was not a mistake, but not getting the right trim and boots may have been. I do not suggest stall rest at all, and agree that snow and ice are good for him. With snow he may not need boots all around, get a specialist to gauge that for you. Likely that one foot needs one until he is more comfortable.