I really sympathise Will.

I'm struggling with similar. I was never depressed before but now my mood feels really unstable, I don't feel like myself and the future doesn't feel very bright to me.
I'm 7 and a half months in (car accident in January) and I've gone from feeling numb to low to very low to episodes of breaking down crying which come out of nowhere.

I've finally taken the plunge and agreed to anti-depressants which I really didn't want to take. I'm a few days in and they're making me feel weirder and less like myself, I hope it passes

I was finding it hard to deal with the boredom too and felt mostly okay as long as I was occupied.

I've struggled finding work and so decided to start voluntary work to fill my time and keep me from going mad.
I've got an interview for that on Monday and then training for a few weeks before I start, but that has already made me feel better, knowing there's something coming up.

Maybe this is something you could try?
It's different for everyone, but I find helping others makes me feel good and there's not a lot that makes me feel good these days.

I've also started making plans (using a diary app on my phone to record them as otherwise I'd never keep track) so each day I have something happening to keep me occupied, visiting a friend, or shopping, or going for a bike ride and this is really helping.

I find the worst times for me are waking up with an entire day to fill where I haven't got anything planned.
I find it hard to get out of bed as there doesn't seem any point. Then I end up sitting on the sofa in silence thinking 'well, what now?'

I hope things get better for you, but remember, the depression is going to be there, PCS is a hard thing to deal with, but you have to take steps to help yourself.

Try a routine, try making plans with friends, or things to do, one a day, maybe try doing some voluntary work if you think that's something for you?

I'm still depressed, but I feel better than I did and I'm functional, but that's because I refuse to let this rule my life

Abbilee makes a good point: it is important to have things to look forward to. Volunteer work is good, if one doesn't allow it to become too taxing. If one isn't ready for that, just planning a quiet outing or anticipating a visit with a friend can be enough to keep us going.

I am also an advocate for pets. I can't meet all the needs of a dog, so I rescued a cat. I may not want to get out of bed in the morning, but the incessant meowing of "fill my bowl," forces me to get up. I'm needed - and I think that's a very important feeling for human beings.

It is very common for GPs to give SSRIs to TBI patients. Please be aware that, ironically, suicidal depression can be a side effect of these meds. If your doctor wants you to take them, please insist that, at least in the early days, you be under the close supervision of a qualified mental health specialist.

I have depression and anxiety. I believe that even though drugs may work temporarily, they are not necessarily the answer. After injury the brain may need help, a boost, to get it operating more normally. I have found that a vitamin regimen works very well and it has lifted my depression and anxiety. B12 (methylcobalamin) seems to do the trick for me, thanks Mark.

The point is, a so called chemical imbalance may not be the cause, but other physical issues may be involved, such as Injury and nutrition. If you can determine the cause, you can determine the treatment.

I have lived with depression and anxiety for years, but that is over now. I have eliminated processed foods (mostly) from my diet and I eat lots of fresh vegetables and fruit, and don't forget good fats and protein. That alone was not enough for the depression, but the vitamin regimen did the trick. So, I conclude that my depression at least is caused by the TBI and is treatable WITHOUT drugs.

Jamie

I was lucky because the doctor diagnosed my PCS two weeks after my car accident. I have been able to get the best doctors. I have had anxiety but each month it is getting less. I haven't been depressed. I got great advice five months ago "this is just a season, it will pass with time".

The first 51 year of my life, everything came easy. The last 6 months every grain I have made has cost pounds of pain. I will get my life back on track, I just don't know which track it will be. I am looking forward to figuring it out.