What could cause this in a 12-year-old?

My 12 year old daughter has had headaches for 9 or 10 months. She was taught to rate them on a scale from 1-10, and what used to be 5's and 6's are now up to 9's and 10's. She says they're almost always worse on the right side. She also has dizziness, nausea, fatigue, bad balance, and weakness. Sometimes she does this thing when she scrunches up half of her face a little(I think to make her head feel better), and she's complained about feeling numb in her face. In February we noticed a hard bump on her neck, almost 1 inch in size, that can move about 1/2 cm up and down. She said she noticed it in December. She also moves her eyes back and forth a lot. We're not sure what to think about all this now, because her neurologist says it's nothing and isn't helping at all, and her regular doctor is convinced there may be a tumor in her brain, even with the clear CT scan in August. No medicines or pain relievers are working. We're kind of worried, because they're getting so bad that she doesn't want to do anything anymore, and is always sleeping and falling over. Any information will be helpful. Thanks!