Aidan, what you describe sounds exactly the same as what I had recently, but not quite as severe. My shin hurt like hell to hop on, hurt like hell to crouch down on, was tender to the touch, pain that came and went (not always related to exercise), and basically had me panicking it was a stress fracture. Went to see my usual physio who diagnosed basic shin splints, gave it a good deep massage - including the soles of my feet and my calves - and it's since eased off a lot.
Most likely you've got shin splints just as that's much more common than stress fractures, but like other people have already said, you really need to track down the cause of it, otherwise you'll rest a bit, it'll go away, you'll start training more, and it'll just come back, probably worse each time.
After a bit of investigating and some slow-mo running footage playback, the cause of mine turned out to be that I was turning the toes of one foot ever so slightly outwards on landing, meaning I was rolling slightly on to the inside of that foot on push-off, which was stressing the muscles over my shin. All compounded by hypermobile joints allowing that ankle to roll around way more that it should be. Somewhat similar to pronation, but not quite the same and not treatable with motion control shoes, as I'm not a pronator, I'm a neutral runner with over-flexible ankles.
Ten other people could have ten different causes, so it's not really something you can take advice for as to what's causing it online. Best to go see a physio or running specialist and get gait analysis so you can figure out what's happening with your feet and ankles when you're running.