I'm sorry to hear about your spell. I have had many like that post mirena and it is scary. I had a few when I was pregnant before I ever had mirena. I had to get progesterone injections when I was pregnant to prevent pre-term labor. It really scared me then. I made it full term and did not have any trouble at all during labor. I did have wierd vision problems. It was just like I kept seeing spots floating around in my vision. The spots improved but did not go away until about 8 months after my baby was born. However, I did not have any more wierd episodes like you have mentioned after the birth until mirena that is. I did find out after the first two bad episodes that my potassium was low. Make sure you have plenty of potassium. Alot of people recommend orange juice and bananas. However, I had gestational diabetis and could not do alot of sugar. I found potatoes and almonds have alot of potassium. It might be worth a try.
Goodluck.