Well we have just heard from the vets. The results have come back clear of any tumours! They aren't sure what has caused her lump but the 2 theories so far are either trauma to the muscle or a haematoma. The swelling in her leg and belly is going down and she is a lot better in herself. Obviously still on pain killers but she actually manage to slip her collar and jump in to the back of the car today by herself (we have been lifting her in).
She's not eating very well though but she is such a suspicious dog anyway that she thinks everything has horrible medicine in it.
So she is going back to the vets on Monday and we will go from there.
Quite glad we didn't just believe the vet and have her pts there and then.