How Long Does A Myasthenia Gravis Crisis Last?

I'm a 29 years old woman, 5'1", 125 pounds, mothe of two. I suffer from myasthenia gravis since 2 years ago. I've been taking mestinon ecer since, and a little bit of prednisone, and so far it was only affecting my eyes, but four months ago I stopped taking all the pills because I was trying to get pregnant, and then a week ago I started having a myasthenic crisis, having a lot of breathing problems. Right now I'm admited at a hospital receiving treatment, and I want to know how long does a myasthenic crisis last?