Right now, I think it’s best to not use any of those supplements if he will even still eat anything. Hydration is most important to focus on. You can try dripping a few drops of water on his head and see if he’ll drink. I hesitate to tell you to put any water in his mouth as their airway is in the front and the risk of accidental aspiration is too high. Also, the stress of that would be too much at this point. Do your best to keep him comfortable. He may go to the bottom and stay there. If he does, you can place something soft under him.
I suspect the problem is with the supplements. Vitamin D3 and Vitamin A are both fat soluble and can build up to toxic levels. Both are used usually only one feeding every other week on an alternating schedule, (the vitamin A usually being in a multivitamin) and plain phosphorus free calcium without D3 is used for every feeding. I’m really not sure if there’s any way to help get the fat soluble vitamins out of his system. Perhaps
@kinyonga or another member can better advise you on this.