This is your body's way of telling you to do neutral and prorated chins, not hammer curls.
You are probably doing something nasty but transitory to the many and complicated muscles, tendons, fascias or ligaments in your forearm, so stick a hockey ball in there and roll it around for a bit.
Also, try some fat bar work for your pulling/pushing exercises...
More than happy to do more and better chins rather than more curls of course, though at the moment I'm limited to an extremely basic bar that means that "wide grip" is just slightly wider than my shoulders :/ Also, the height isn't great. Still, can't complain given my living circumstances
I really do need to do some mobility work. I guess that is certainly a good portion of my problems, though I also imagine that I'm jumping up on my weight too soon and my form needs work (though I realise that improved mobility will help improve my form). I've also had a sore neck for a couple of weeks now since trying to do more of the DB sessions which I'm pretty sure is down to me not keeping my neck neutral during the various routines.
So... a few noob questions:
1) "neutral and prorated chins" - can you expand on that, in laymen's terms?

I can make a guess as to what it means but I'd just like to get it nailed down so I can be sure I'm doing the right thing.
2) "fat bar work for your pulling/pushing exercises" - please can you expand again? I'm guessing you mean using a proper barbell rather than crappy dumbbell? If so, I'd really like to but I can only get away with having so much stuff in the place I live right now and my time constraints have stopped me going to a gym. I'm actively looking for a proper gym so nearby so I can get there and do a decent routine but for now.... I'm stuck with what I'm doing (posted below, just to spam the hell out of the thread).
My current routine is below. I've been really bad about it and have generally done something along the lines of do it every day Monday to Thursday or so and then take a couple of days rest. On top of this I do quite a lot of cycling.
(all below with DBs, weight is per arm obviously)
Day 1
Bench Press 4 * 8 * 25
Close Grip BP 3 * 8 * 25
Skull Crushers 3 * 8 * 12.5
Overhead Press 3 * 8 * 15 (lolz)
Lateral DB Raises 3 * 8 * 7.5 (cry)
Squats 4 * 8 * 27.5 (still finding my feet with these vs proper squats)
Day 2
Chin Ups (Alt. Grips) 4 * 8 (underarm/overarm)
Curls 3 * 8 * 17.5
Hammer Curls 3 * 8 * 17.5
BOR 3 * 8 * 22.5 (another one I'm still finding my feet with)
Rollouts 30
Squats 4 * 8 (as above)
There are a few times I don't do the squats (I know, I know) if I have particularly intensive cycling days to follow.