Thank you for everyone's input. It is worrying. I went for a 3 mile run with her this morning that she was very happy to do.
Not around her meal time usually. I agree her body language spells 'scared'.
The reason (or one of the main reasons) I drive to where I walk her is so that she doesn't have to walk on pavement-I live near a country park, all mud and grass and dusty footpaths.
If I walk with her to there, ironically she's fine (if she'll leave the house which she mostly will) it is just when I drive there with her she'll refuse to exit the car! But again, never on a morning. Evening she'll refuse (as in the case of starting this thread) a bit later on in the day she's began refusing too!
@BeBopBeBop yes-it does make you realise just how short their lives are doesn't it. 
I asked the vet specifically about arthritis and he said definitely not, she's fine, maybe stiffer than a younger dog that's all but that's perfectly normal in any animal (me included 
).
I do walk her in different places, as it is just me and my dog I try to 'do' things with her, it just isn't practical on a day I am working. There's also a park down the road which I'd like to go to more but for years she's refused to get out of the car there! It has a bit of a reputation for teens hanging about there smoking etc, and some locals refuse to walk there due to apparent nefarious activity but I haven't ever looked into it and the teens smoking thing wouldn't put me off-but dog just doesn't like that park at all!
@Potsnpotz the gym I go to is half in and half outside. It's an old bodybuilder's gym, It's very cold (even in this weather it is cool, which I thought dog would like and she definitely seemed to at first). It's also very quiet, only 50 members and most have their own keys at is is likely that one will turn up and nobody will be there. It isn't manned. There's an option to turn music on but the only time it is usually switched on is of an evening if it is 'busy' and by busy I mean about 6 guys in, lifting heavy together. I have a key and during the day I am rarely not alone there-if I am not it is usually one other member. A lot of us take our dogs in-although if others are there I always have popped my head in and asked if everyone is okay with it before I do
The first couple of times I took her, she'd just sit next to whatever I was using, seemingly very chilled out, enjoying the cold floor-then I'd move onto the next thing and she'd come with me. She seemed very happy there-alas after that, again she refused to leave the car. Obviously if I was a member of a loud, busy, chain type gym I'd not take a dog there.
I am going to do what is suggested by a few of you, take the dog back to the vet and ask for some pain trial medication.
@sunsetsandboardwalks I really don't think she's struggling to exit the car though. At my Mum's that time, she LEAPT out of the car like a 6 month old pup and same when I take her to the pub most of the time. Plus I drive an old sports car-anyone over 5'6 struggles to exit it as it is practically on the floor!
@sunsetsandboardwalks he checked her paws and eyes-not sure about hearing come to think of it!
@FinallyMovingHouse those dogs are known for being trained to know their own mind aren't they! I love them.
Mine is a mongrel-part timber wolf part husky part malamute. I think someone thought 'hmm what'd happen if I stuck the most naughty/stubborn breeds altogether...'
She's reluctant to get out of the car at the gym at any time @fortheloveofcollies love-I've tried day and eve although I don't want to again as if she won't i'll have to come all the way back!
I use the car for morning walks too-It's quicker so better for before work and not as boring a walk. Can't think of anything that's happened or anything different. I Agree, I'd love to get to the bottom of it!
@Thunderboltandlightningveryveryfrightening part husky! But will not go out after dark at all unless It's to the pub!