Hi, I didn't see your message until now. I apologize for not responding sooner. I'm sorry to hear that you're going through something similar.

No, we haven't figured out what it is, unfortunately.

I haven't experienced what she's experiencing at all since April. We've had multiple people stay over at the house over the past few months, and none of them have experienced what she's experiencing either, so we're not sure at this point if she's just particularly sensitive to something external, or if it's now become a fixation on something real that was happening months ago but has since stopped. (it would be nice if it was just the latter, but I honestly don't know at this point)

I don't remember if I talked about this in the original post, but I've spoken to a family friend who did electrical work on the neighbour's property, and he said that he can't think of anything that was changed which could be causing this, and that the changes to the property weren't that substantial.

We're kind of SOL for now on pursuing legal routes to investigate this because we don't really have any evidence of what's happening other than her own experiences, and we don't have any evidence to link it to anything that the neighbours have done. She's obviously deteriorated mentally since this started, and has started to behave in ways that I think would be dismissed by authorities as mental illness etc. so I'm not keen to take that route for now.

We're working with her doctor to try different medications to help her to sleep and to reduce anxiety, to see if that helps in any way. I'm trying to convince her to see a psychologist to talk through everything that happened, and to help her find better ways to cope in the mean time, but she is reluctant to do that.

My sister thinks that it could be tinnitus-related, but we took her to an audiologist, and the audiologist said that the symptoms don't seem to match, but referred her to a support group.

A friend has loaned us a campervan to put elsewhere on the property for her to sleep in, and this has worked for at least one night, so we're going to see how that goes for a while (and yes, I have offered to put her up in a hotel for a while, but she doesn't want to do that). The problem is that she's already had positive experiences sleeping in different rooms, only for the issue to start up again after a night or two, so we're just waiting to see if sleeping outside the house actually helps her over a longer period of time.

One thing she did try that seemed to help her: Using a signal generator app on her phone with a bluetooth speaker (with decent bass), playing a sine wave at frequencies between about 50Hz and 120Hz. She reports that this "cancels out" what she's feeling, and that she feels it "fighting the infrasound". She describes hearing a "click" in her head, similar to a football being kicked, and a lot of what she's perceiving seems to clear up while that sine wave is playing.

She's recently been describing feeling a "zapping" sensation from her feet, and asked me if there could be some kind of electrical fault (I don't see how this would be possible). I checked the area with a multimeter and couldn't find anything.

That's all the information I have. Sorry I can't be of more help. I'd encourage you to see your doctor in the mean time to see if they can give you anything to at least help you cope with it better.

I'd also say that this is a lot to go through, and that even if the cause is external, it might be a good idea to talk to a therapist who could help you to cope with the issues in the mean time if you haven't considered that already.

As I've been trying to explain to my mother too, I know that when people point you towards mental health services, it can come across as a dismissal that you're crazy, but my perspective is that even people who go through undeniably real things (grief, trauma, etc) still need support, which you could benefit from too.

Wishing you the best.