So recently I have started to get an itchy bum (the anus rather than the cheeks) and I am trying to figure out why. It typically occurs in the nighttime but sometime during the day too. It's not constant however, it comes on intermittently.

I do not believe it is an STD, there does not seem to be any sores/rashes,  no pain, no pus, no discharge, none of that stuff. (Although granted, I'm finding it difficult to use a mirror to look deep up there. I might need to use my phone instead).

I have a few theories:

1. I was bottom for this one guy a year and half ago now. I was pretty new to bottoming, and instead of using normal lube I used massage oil as lubricant (silly me). For about a month after that I was getting anal itches throughout the day, pooping red and painful (felt like tearing when I pooped). However after that month or two, it healed and no more of it. Until now, could this be another outbreak from that? It's been a year and a half though?

2. Sometimes my nails are a bit long, and when I showered last month, whilst washing up there, I may have scratched the lining? I shower in quite hot water as well, so this may have exacerbated it? Could I have damaged my lining and causing the itching?

3. I notice that when I go to itch my bum when I can't stand it any longer, it is moist. Like, it's wet. Not like dripping wet, but it's definitely noticeable. Is this sweat? I have read that a sweaty bum can be the cause of itching. However what is the cause of sweating? I can understand if I do loads of sport and then not wash myself, it may cause itching. But I am in quarantine and sitting on my ass all day, why is it moist up there? I have made sure to dry myself properly after shower, so it's not latent wetness from that.

4. I have also recently noticed that when I poo now, there is a split second when it feels like my lining is tearing a little, i.e. that tearing stinging feeling. It's literally for a split second. But this is not normal, I have never had this feeling before. Does this suggest that my lining has weakened (maybe form the scratching?). If so how do I make it heal?

5. Could it be to do with hair? I am not a very hairy guy (in fact, I am very smooth), so I have never shaved in my anus. Maybe the hair down there has grown slowly over the years to a point where it becomes itchy? Is this possible? Maybe I just need to shave?

And also I haven't bottomed in like the last year as well, so it's not from that.

Any insight appreciated!