What was it?

Cross posted from NiH because I don't have the energy or courage to go through this memory twice.

I like being able to explain things. I'm an annoying know-it-all-wannabe. I shout out the answers during Jeopardy!.

I cannot explain what happened today, and that scares the shit out of me more than the actual event itself. Even if I could, no one would believe me, or they'd think I imagined it. Geez, if I'd been in a dark room by myself late at night, I'd chalk it up to imagination; but this was broad daylight. I reacted physically. I can't recall anything like this ever happening, exactly. Maybe I repress things, I don't know. Why now? Why would I sense something now?

I was exploring an old fort that's a tourist attraction, locally. I wandered off to a side of the fort where some workers were digging something, but still a ways off. I went down some earthworks towards a demi-bastion and some ruined buildings near the outer wall where there was no one. I looked, before and after, and there was no one about.
I peered into an old kind of store-room or something tiny, then turned to go into the next archway, which led to a larger room, I don't know what purpose it was, but it had a window, so I think it couldn't have been just a store-room, maybe a living space of some sort--all the other store rooms in the fort had no windows.
All of the rooms I'd seen were damp, being unsealed against rain and probably with things seeping through the cracks in the rocks--there are no proper roofs, really. Most of them just had the general smell of wet rock, moss, musty water, and the ocean.
Facing this room, though, which looked no different, I was hit by the overwhelming smell of something sick but sweet--kind of like the smell of spoiled meat, or like when something washes up on the beach and dies. (And this was in a place higher than the sea.)
At the same moment, close by my right elbow, but at the level of my ear, somehow I heard this sound. It was like a scraping hiss or someone gurgling or growling with an open mouth. It was short--less than a second, but quite loud, as though it were right beside me.
I felt like I wanted to run, to turn, to leave; but it was more than that--I felt pushed. Not physically, but I felt very much that something there wanted me to leave, to just be gone.
I got out.
I wandered around the grounds outside for a while in a bit of a daze, then just sat on this old staircase of flat rocks set into a slope of the earth, and just stared out at the sea.
I'd like to think the history of the place might've just impressed itself on my imagination; but that smell...that sound--they just didn't seem natural; and I felt so very strongly that the reason for my leaving that spot just as much belonged to something outside of myself as my own will.

...if anything like this ever "happens" it's just me lying in bed trying to sleep and scaring myself with rehashing other people's spooky stories in my head. To have something like this happen, unsummoned, and in broad daylight...gah. I've never imagined anything sensory, either. I want so badly for this to have been my imagination.