Have you been prescribed any medications or been to see a doctor that specializes in concussions?
I've been reading the posts online and some have had success with anti-depressants and/or sleep meds, physiotherapy and ginger tea/drinks for the nausea. As for me, I just started on a small dose of anti-depressants for the migraine headaches and also see an osteopath, massage therapist and get Reiki treatments from my physician. Now this doesn't solve everything, but it can help with the mood since I know that trouble sleeping and all the symptoms we have is enough to make us go crazy. The other night at around midnight I was so restless and irritated that I went out for a brisk walk eventhough when I did I could barely see, I was dizzy, nauseated and I've been told not to do any physical activity.
It's very hard and I imagine 18 months feels like a lifetime. 3 months ago I would have been having a great REM sleep at this time and would have got up at 5:00 a.m. to go to the gym. Now I don't even remember what a good sleep feels like.