So for a short background, I’ve had depression for around 4 years now. I am currently 15 years of age and the depression started due to severe bullying and my abusive parents. 

Around 2 months ago it had gotten better and I wasn’t feeling suicidal. I was a little down at times but nothing that serious. However, it’s come back but now it’s different. I’m now having pretty big mood swings such as earlier when I was just relaxing watching videos to now crying and wanting to take my own life. I was wondering if it’s possible for clinical depression for 4 years to suddenly change and turn into bipolar depression?