oh that poor baby :-(
I'm no expert but I think I'd try standing the baby up on it's feet and waddling a towel around it's legs to keep it upright, then see if I could get some vitamins/food/water into it. It's definately losing it's balance which might mean a neurological problem. I suggest waddling it up because I imagine it's getting dizzy which could be stressful , perhaps if it can stand still and rest a bit as well as vitamins, food and water it may get it's balance back. Like I said though, I'm no expert.
This baby looks like a fighter to me, I hope you can bring it around to live a long and happy life.
Michelle