Minirin works by increasing the amount of water that is reabsorbed by your kidneys.
When it is given in higher doses, it can also raise your blood pressure.
Because the medication is causing your kidneys to reabsorb water, this can lead to your sodium levels to drop.
If your sodium levels drop too much, this can make you very ill. At sodium levels of 120, you can feel nauseated, more short of breath, dizzy, fatigued and be vomiting.
So, much of your symptoms were likely due to your low sodium, which was due to the minirin.