Bug - can't run, jump or use weapon?

[gnewna]

So, I have installed three new mods, and I was very bad and didn't test them all individually before I started playing. It was actually four, but I got this bug early on and thought it was one particular mod so I deactivated it, reloaded to before it was added in, and carried on.

Basically, the bug prevents me from running (I can walk), jumping, or using my weapon. I didn't think to check whether I can still cast spells or activate items. First time it happened was when I was harvesting Morning Glory flowers in Anvil, so I assumed it was the 100% Harvest Chance mod so I uninstalled it, seemed to fix the problem, so I carried on. The other new mods are Better Cities, Kyoma's Journal Mod and Side's Backpacks. After I reloaded, I played for an hour or so, did the Anvil Mage's Guild task, reported back, wandered around town, went off to the Fort just outside town, killed some baddies, then suddenly when I switched from my bow to my dagger (which I had already done several times) the same problem arose - can't run, can't jump, and clicking my mouse does nothing.

Any ideas what this could be? I also made a couple of .ini tweaks, just to the amount of grass loading and zoom level when speaking to NPCs. (I've tried to google the problem, but am failing to think of a sufficiently specific search term that doesn't just bring up a million irrelevant things, and that isn't *too* specific and comes up with nothing at all.)

[gnewna]

Oh, also, I have the unofficial patches, and am running about half of the DLCs, other mods include DarNifiedUI, Natural Faces, Travel Cloaks and Alternative Start - Arrive By Ship. I've run LOOT.

[gnewna]

Curious and curiouser. I went back into the game and it seems to be specifically the dagger that's the problem - I switched back to my bow, everything was normal. Switched to a warhammer in my inventory, everything was normal. Went and dropped the dagger I had so I had inventory space for a nearby claymore, equipped that, everything was normal. Picked up the dagger, dropped the claymore, same problem. Added a steel shortsword to my inventory through console, equipped that, everything was normal. Picked up the dagger again, equipped it, and everything seems back to normal with that as well. WEIRD.