I can definitely relate. I’m also 27, and I’ve had nausea and dizziness since my concussion in January. It seemed to taper off for me around the beginning of June (so about six months) until I hit my head again and now I have it every day, along with headaches/migraines. My CT scans (spine and head) also came back fine and I’m also doing physical therapy, which helps with the headaches a little bit but not the dizziness or migraines. Good luck with your symptoms! I know how frustrating they can be!