Undergraduate / "Struggle and success: I completed the courses with all A's" -significant experience [3]

So, I'm working on an essay for admission to a college and I'm not the greatest at writing.
Any help is greatly appreciated!

The Prompt says to pick my most significant person, experience, or circumstance that has changed my life so far. It also says to explain how it has influence my character and how I can use what I learned from it to achieve my goals.

My Essay:

Many people get sick throughout their lives, go to the doctor for medicine, and get better. Then there are the lucky few who experience a mysterious illness. No doctor can diagnose it or find any medicine to give them relief. This would be where I fall in. My sophomore year in high school is when a mysterious illness came into my life. From that day on my life will be forever changed.

I started off going to class regularly and trying my best to keep up with all my new classes. All of a sudden I began to have a very persistent stomach pain. The pain became almost unbearable. It caused me to spend a numerous amount school days in the nurse's office or at home. Attending different doctors and having multiple procedures turned out no results. Because of this, for my second semester my counselor and family decided I should try a type of home schooling. It seemed like a great idea in the beginning, but ended with me not understanding and failing classes.

I decided to go back to school for my junior year, looking for a better outcome. The cycle of missing school eventually started all over again. My grades were slipping down to failures and my health was even worse. With help from my counselor, it was finally decided that for my senior year I would go to an alternative school. This school was a way for me to work on all the classes I needed at my own pace. This decision changed my life. Because I was behind there were 9 classes that I needed. I ended up finishing all of these courses in 3 months. It was the most amazing thing to know that I had accomplished something I stressed about for two years. To make it even better, I completed the courses with all A's.

Ultimately, this long struggle that ended with success has affected me greatly. It has given me a positive attitude and patience with knowing that even through down fall good things can arise. If I try to achieve something, with hard work it is possible. This experience has allowed me to know that on my way to accomplishing my dreams in the future that as long as I continue to work hard I will get to the goal I aim for.