PredniSONE and 19 years old

I am 19 years old and I recently was taken off of it 2 years ago when I switched doctors. Prior to the switch I had been on it for 16 years. I prob have some of the worse side effects. Because it causes an increase in appetite I ate but I didn't eat all the time, and I ended up gaining over 100lbs. I have a black-brown ring around my neck and for the longest time I thought it was dirt that wouldn't come off so sometimes I scrubed my neck sometimes to the point that it was raw.I have bad acne on my back and its just horrible.I cry every single night because of the side effects.I just want to know if anyone on here can help me.

I am 19 years old and not even 5 ft tall. Basically, I'm very small. I went to the doctor for an upper respiratory infection due to neglect of my asthma. My doctor gave me a prescription for 3 20mg tablets of Prednisone per day for 5 days. After taking it the first day I started experiencing high anxiety attacks, insomnia, and began to entertain suicidal thoughts. Thinking it was all due to stress, I sought help after taking a total of 300 mg and come to find out that the prednisone may be the cause of everything. We are not sure yet if this is true, because the drug is still in my system, but all clues point to that.