history: I worked really hard to get into a program that I wanted to be in. Unfortunately, it was too difficult for me and I had to change majors; I was pretty upset with myself. I put a lot of effort and time into getting into a college program I wanted to be in. oh that sounds like it will be very rewarding!
current: Unfortunately, I had to switch majors; the program was too difficult to stay in and my mental health was deteriorating.
next: a tough situation but at least you were able to realize and adapt!