The 18-year-old, who lives in South Uist in the Western Isles, began experiencing problems when she was 15.
"I had a bit of a hard time when I was younger with bullying and abuse, but I had put it all behind me," she said.
"We moved up to Scotland. We had a good life, I was happy and then all of a sudden, once I could relax, there was something going on in my head. I was getting paranoid and stressed."
During a camping trip, Gemma started hearing voices. "They were telling me I was stupid, I was lonely, why would they want to hang out with me? It started to really scare me."
A friend's mother, a doctor, prescribed medication and referred her to a psychiatrist. Gemma was eventually diagnosed with post-traumatic stress caused by the earlier bullying.
With medication and counselling, she was able to deal with the illness. Gemma said her school, and the headmaster in particular, was very supportive, but some teachers did not know how to handle her condition.
"They were just making sure I was OK all the time, and that draws attention to you in class, which makes all the other students want to single you out."
She was off school for two years but is now studying for her Highers, after which is wants to go to university to study aero engineering.