Can I really have TMJ as a 17 year old?

I'm only 17. I had braces, but I got then off when I was 13. My teeth aren't really that pretty any more, and my bite is kind of off.

A little over a month ago, my jaw was stuck shut and I couldn't open it more than an inch. My dentist referred me to an oral surgeon, who confirmed that my wisdom teeth are badly impacted and gave me muscle relaxers to open my jaw, which worked. He figured that would be the end of it.

However, soon after stopping that, my jaw started to click if I opened it too far, and crack a few times a day. I went back to my oral surgeon, who said that because I'm 17 he wasn't concerned, and that it was probably the remnants of that massive muscle spasm acting up, especially because I still have those wisdom teeth. It got better after a day or two, so I believed him.

However, a few days ago, a friend of mine pointed out that my mouth opens very much to the right. She's correct. I also have a slight limitation on how far I can open my jaw, but not like before.

I have an MRI scheduled on Thursday, and I know nothing can be done before then, but I'm kind of freaking out. Can I really have TMJ as a 17 year old? I'm not in much pain now but I'm otherwise very healthy and between this and having MRSA last month I'M FREAKING SICK OF IT! Is there anything else that this could be?