Colin Wilson coughed up some electrons that declared:

I would suggest that you take the advice that was given by NHS Direct

Ooer, that's 2 votes for the hospital... i'll see if it improves
overnight and may have to consider a trip tomorrow...

If I croak in the meantime, nice knowing you all (i'm not covered for
disability on my mortgage, only death, so if there's no easy cure the
missus is better off getting part of the house paid for...)

The pain did originally start on bending or straightening after
lifting stuff (i.e. a box of A4 paper), and about a month ago it felt
like it was starting to "lock" if I straightened it out - around the
same time I started to get a bad burning sensation in the elbow, but
it felt like a really nasty chemical burn, not the normal sort of pull
/ twist.

I've just had to kinda dangle it for the last few days, I can't move
it by itself, i'm having to flop it around with my good arm :-}

The worrying bit is the "good" arm has started to give that burning
sensation too...

I'd concur. Funny colours and numbness would have me straight down the
out-of-hours surgery or A&E. I'd be nagging for an MRI or at least an
X-ray.

However, take heart: I've had a hint of RSI and a dodgey kneecap in the last
few years and a few sessions at physio fixed both of them. Don't know what
your problem is, just saying that physio can do a lot these days in lieu of
surgery for certain joint problems if you get it early.

My "RSI" was simply a nerve getting caught (lots of tingling and some
pain) - the exercises I had were to encourage the nerve to stretch so it
could run easier over the joints. The knee was a kneecap slightly out of
place - again, excercises to stretch some ligaments to encourage it to
settle in a better place.

Good luck

Tim