Nikki, you poor love - you're really going through it, aren't you?
I'm a former neuro nurse, albeit from way back when, and I have to say at the outset that I don't think you need to go down the pathway of dementia or a brain tumour. Post-concussion syndrome can go on for many years, sometimes a lifetime, and is already enough to account for all your symptoms.
What's really bothering me is why you've had to go on antipsychotics or, more precisely, whether you still need to be on them now. But please don't stop or even reduce the antipsychotics without strict medical supervision, as this can cause major problems.
Both antipsychotics and antidepressants - but particularly the former - can cause mental slowing. You're clearly reacting badly to your antipsychotic meds if you're getting tardive dyskinesia. I know what this can be like as I saw a dear friend going through it when she was put on clozapine. Medications affect different people in different ways, and there are many other antipsychotics which might not cause the same disastrous side-effects.
I'm very glad to hear that your GP has referred you to a neurologist. That's the specialist you need to see.
But I'm still flummoxed about the antipsychotics. It's true that some people go through mental changes in the immediate aftermath of a head injury (or indeed brain surgery - which is a type of injury in itself). Antidepressants or anti-anxiety meds may be necessary to control this, at least in the early stages. However, it's very rare for post-head-injury patients to be put on antipsychotics. Can you tell me who prescribed these drugs, and whether they're being regularly reviewed? They should only be prescribed by a psychiatrist, but far too many GPs are getting in on the act these days, without having the necessary knowledge. That's what happened to my friend, with disastrous consequences.
The next question that comes to mind is: why are you on antipsychotics? Did you have a full-blown psychotic episode when recovering from the head injury? That's quite rare, but can happen. However, it's not common to treat this kind of episode with antipsychotics, and certainly not long-term.
You also mention epilepsy. Has the head injury left you with epilepsy? That's not uncommon, I'm afraid. However, even if it did, I don't think the epilepsy would be the cause of your brain fog. It would be more likely that both are the result of the head injury itself.
I'm sorry if I'm asking too many questions, but it seems to me that these might be questions your GP should have asked, and perhaps didn't. There isn't really enough information in your post to shell all this out.
You don't have to answer, of course. I'm no authority, just some old dame on a patient forum! But it might help to formulate some of the questions you need to ask the neurologist when you get there. If you don't want to answer in public, you can send me a private message by clicking on that little envelope icon underneath my avatar. PMs via this site don't carry viruses, and they don't expose the email address of either party.
And once again, please don't stop or reduce any of your medications, particularly the antipsychotic. This has to be done over a very long period, and only under medical supervision.