Gross but help: LICE

Seven weeks ago, I went home to visit my family. I was in a hurry and used a random hairbrush in my house, knowing it was my 14 year old sister's. I know this sounds like a bad idea, but she is the glammest person I know: she looks like a mini Kim Kardashian, is the queen bee of her friend group in high school, and is constantly showering or doing her makeup or working out. She's like the definition of hygienic, so it came as a huge surprise to find out a few days later that she HAD LICE. Apparently she had gotten it from her best friend's younger brother. I was terrified that because I had used her hairbrush I had it too. However, she does have about 50 hairbrushes, so there's no guarantee that she had used this one recently. Ever since, I've been on the lookout for lice on my own head. I've had dandruff my whole life, so I always have a moderate amount of itch and flakes on my scalp, making it really difficult to distinguish between lice or dandruff. I have found a few suspect "flecks" in my hair: they are yellowish white and seem to stick to my hair strands. But I still haven't seen any lice, and again it's been almost two months and I haven't felt an abnormal amount of itch. I've had lice in the past ten years ago and I was itching CONSTANTLY. And the nits were more brown and slightly see through, and I haven't seen those yet, or any bugs. I feel like I'm in denial though: I'm afraid to admit to myself or anyone else that I have lice, but I want to get rid of it before it gets worse. DO YOU THINK I HAVE LICE? HOW LONG DID IT TAKE FOR YOU TO EXPERIENCE MAD ITCHING AFTER CONTRACTING LICE?? HOW DO I CHECK WITHOUT TELLING ANYONE? WHATS THE BEST LICE TREATMENT FOR THICK HAIR???