I was guessing bluetongue myself. We had it hit here and there through the years here in Missouri. My brother was bowhunting a few years ago when a scrubby little doe came stumbling up the path. When she got closer, he noticed a huge goiter under her neck. He had intended on letting her pass and let nature take it's course, but she was struggling and then she tried and tried to scramble under an old fence in the woods. He had enough, and decided to put her down. He put an arrow through her and left her lay.
She wasn't fit to eat anyway.
I agree with the others. Put that deer down. It may help keep the disease from spreading.