15 year old w/ Neurologic problems?? PLEASE HELP

[hartage]

hi! i'm a 15 year old female, and all the sudden in december 2016, i started to have neck and back pain and extreme headaches and eye pain, i went to get an MRI and other tests, (nothing wrong was found) and eventually those headaches subsided. in february 2017, i started to have severe chest pains and pain in my left leg, at first they thought it was a blood clot, but it wasn't. the chest pain subsided but the leg pain stayed, it literally feels like a muscle that has tightened up and will not let go. but recently, starting last week, my leg has started twitching like mad, and my other leg has started up twitching too.

honestly,  i'm so scared that i might have some neurological disease that would leave me paralysed like ALS or MS and all the tests that my doctors are doing (MRI's and such) are coming up w/ nothing! i'm at a loss, and my parents are too. i really just want to feel better and they can't find what's wrong with me? could anyone please help me?