Here's my story so far, for if it helps anybody. Please comment if it relates to you in any way.
Day 1 - The start
I was at the office and I heard a weird roaring sound in my left ear. I went to the bathroom, held my nose and blew to relieve pressure like on a plane, but it was obvious this some some nerve-related thing and nothing physical, because the noise wouldn't change due to pressure or movement.
Month 1 to 3 - Strange sensations
The above only happened a couple more times and I thought nothing of it because it would only last a couple of minutes
Month 3 - Roaring turns to beeping
I woke up one morning and it sounded like I was on a plane, roaring noise. I went for a walk and a swim, but nothing would make it stop. It got better in the evenings but I was waking up with it each morning. This happened for a couple of weeks.
Month 3.5 - Temporary deafness
I woke up one morning and suddenly the roaring turned into a high pitch beep, mainly in my left ear. At this point I immediately knew it was tinnitus and possibly perminant - so I got very worried.
Additionally, for a 24 hour period, I lost almost all my hearing in my right ear. I was scared that I was going deaf quickly. Thankfully, after 24 hours it returned, and although my right ear is slightly below normal on hearing tests, it's no longer a concern (touch wood).
Month 4 to 8 - Constant beeping
Thankfully, during the day I often barely notice the tinnitus because of general sounds around. But when sleeping at night it's there, varing in volume. Sometimes it stops me sleeping, sometimes it doesn't.
At this point I also realised that a roaring sound I've been hearing for years when I put my hands near my eyes is not actually normal and is a form of tinnitus. This has increased in intensity since this tinnitus started. For example, if I touch anywhere on my face, I hear a roaring sound now - whereas before I needed to touch my eyes. (It's worse when I'm tired)
Month 9 - Present Day
Weird new symptoms started recently. I woke up earlier than normal and had that super tired feeling on Christmas day. During this period of extreme tiredness, every time somebody talked, it was distorted/accompanied with a background roaring nose. When they stopped talking, no roaring noise. (Just the usual beep).
This died down as the day went on and I woke up fully - but it was a new thing.
Today, the tinnitus is mainly annoying because of worry that it will get worse or hinder my life, although at the moment it thankfully isn't doing that so much.
Today, I have perminant high pitch tone in left ear, and intermittent low pitch tone in right ear. Both vary in volume.
How I help myself
If I can't sleep, I ask Google Assistant to play nature sounds, it plays cricket noises which are excellent at masking the high pitch tone. I recommend cricket noises to anybody trying to get to sleep.
I can't control the tinnitus, but I can keep myself healthy in every other way to make up for it. Good diet (trying) and regular exercise helps me.
My background and potential cause
11 years ago some neurotoxin got absorbed into my skin over night. The next day I got tingling sensations on my skin, which resulted in peripheral neuropathy, causing low intraepidemal nerve fibre density - diagnosed about 1 year later. Since then I've had crinkled and pink finger tips, and foot pain when I stand still for more than a few minutes caused by this. (Apparently it's auto immune)
I'm convinced that this underlying nerve problem eventually caused my tinnitus 10 years later.