Don't be afraid. Its very likely this is temporary. I know its treatable. If you don't make a big deal out of it, neither will she. The last thing a 12 year old wants is to feel self-concious.
7 years ago my 20 month old was diagnosed with myoclonis. He couldn't even sleep, he would "seize" about every 40 minutes. They were mild jerks, not real epileptic - type seizures. One of the meds prescribed was Klonipin, or Chlonazepam. I think it comes in chewables. It was a very safe drug. I know of two other girls in his class that have taken it. Ethan took it for about 3 years until we were able to wean him off. Now the only time he jerks is right before he completely falls asleep, and it doesn't wake him up.
Don't be afraid of the meds, just research them. Ask around, its likely that another student in her class takes anti-seizures.
Get a 2nd opinion if you want, or just follow the lead of your dr. Although I mentioned a medication, I am not in the medical field and am unqualified to prescribe meds.
The drs. told us he grew out of it, but we believe God healed him. Either way, we're both getting sleep.
Hang in there. You sound tough. You'll make it!