Hi, I'm new to the thread and have never posted before, and wasn't sure where to put this, though seeing as I have OCD and not a panic disorder I thought maybe this section.

Basically I am 18 years old from Australia and have been at university for a few months now. I have always been an extremely confident public speaker and loved performing on stage, and apart from the usual nerves before you go on, have never been worried or uncalm in public speaking situations. Today at uni we had to do group presentations, and beforehand I was completely calm, right up until the point I started speaking. A few seconds in, my voice started shaking as if I was about to cry, I was stumbling over my words, my heart started racing and I started to panic and shake. I didn't have a full on panic attack, but this was the first time it had ever happened. I got through about 30 seconds worth of speaking noticeably panicked before it was another speaker's turn. I regained myself to speak my next part and convinced myself I would be calm, but the moment I started speaking again it got even worse. It reached a point where I was rushing through it as fast as I could without even registering what I was saying, my voice cracking and shaking the whole time, the thought of people watching me and seeing me break down up there making it even worse. Like I said, this wasn't a full on panic attack but it's the closest I've ever come to it and this had NEVER happened before. Now I am entirely confused as to why this may have happened, and the only things I can think of that may have had a slight contribution are:
1. It had been awhile since I had publicly spoken (though that had never been an issue before)
2. I have been smoking more marijuana lately
3. I am on roaccutane which has caused me to become more depressed and moody
4. The OCD, which is luckily not too bad, though I have had this since a young age and it has never affected this before

I'm sorry for the long post, but does anyone have any theories as to why I out of the blue lose it? I really don't want it to happen again