Posting for high traffic as I am totatally unsure of what to do in this situation.
I live in a small block of flats (3 floors), I live on the top floor with my toddler.
The woman who lives below me has been cusing trouble for me for some time. She was fine when i first moved in but after a few weeks I started to find out from other neighbours that she is making up stories and rumours about me 
Shortly after I moved in I unfortunately went through a terrible miscarriage. It was around this time that she went out of her way to tell the neighbours that I am a prostitute! 
Granted, I had 3 men (along with women) coming to and from my flat (My son's father collecting his son and helping me with childcare while I was bed bound, My boyfriend because well, he was my boyfriend, and a mutual male friend who ran a few errands for me).
That was really upsetting for me as you can imagine, I've just lost a child, sex is the last thing on my mind let alone prostitution! I know she didn't know my circumstances but that is still no reason to spead such horrible rumours is it?
She works with my landlord and although she has never said anything like that to him, she has complainined about me 'running round screaming and jumping on the bed at 2am' When she claimed that this had happened I was sleeping on a blow up bed the opposite side of the flat as I had not yet brought a bed to sleep in. Plus, I would have been sleeping and unable to scream without waking my son up. So have no idea where she is getting that from.
She has also complined 4 times (that I am aware of) about my son banging too much when he is toddling around.He is 20 months, I cannot physically chain him down all day long. Luckilly, my landlord is lovely and just ignores her and assures me it is not as problem as he understands children cant just sit down all day.
She has in the past saidbad things about other neighbours to me. My other neighbours are lovely :)
This morning I was speaking to one of my other neighbours that had borrowed my vacuum. He told me he spoke to her yesterday as he had had a complaint and wanted to try and find out who he had disturbed. She apparently said 'well it might be her on the top floor, she has always been a bit of a funny one. yes, deffinately her'. I have spoke to this woman 3 times since living here. All 3 occaisions it was short and sweet and nothing was said out of the ordinary. (Disclaimer: It most deffinately wasn't me who complained.)
I'm getting tired of these constant accusations and rumours from a woman who doesn't even know me. I'm tired of her complaining over nothing. I wouldn't mind if she came up and said something to me so i could at least try (not sure how) to be more quiet. But she just runs off straight to the landlord.
She is causing problems in more ways now. The past couple of months she/ her 20 year old son have been waking my son up throughout the night slamming doors in arguments, or him coming home drunk and screeching singing at the top of his voice in the middle of the night in the hallway.
I haven't said anything as of yet because I am not normally the sort of person to do so. I was aware when moving into a block of flats that there would be some noise from neighbours, I was prepared for that. But it is getting out of hand.
I guess what I am asking id would it be unreasonable to find her landlords details and complain about her noise for once? I know her landlord couldn't do anything about her making rumours, I don't think there actually is anything I can do about that :(
Wow, this was long sorry. It's probably more of a rant then anything :(