Relapse after accutane isn't uncommon. How bad is the relapse? Is it just mild acne or a few spots here and there? Because that's normal - most people who get clear from accutane still get a few pimples now and then.
Usually, if the relapse is severe enough, your dermatologist will prescribe you a second course of Accutane.

Btw, what dose were you on? I'm on 20mg at the moment. When you got completely clear, did dark spots or any hyperpigmentation fade away too?

It's a very bad relapse, it's also progressivly getting worse each day. I was on 20mg for the first month, 40mg for th second and third and 50mg for the forth and last month. I still have a lot of hyperpigmentation scars