saddle fitting help

[fairhill]

Chloe went lame in front a few weeks ago, but only under saddle and it looks like her time off, and the grass, combined with my mum not sitting straight had caused her some muscle damage in the shoulder from a slipping saddle. The swelling has gone down now, she's sound, and the saddler has suggested a wider saddle for her. So we've got a second hand xw saddle to try for the week, and it looks ok, but is tipping up and down slightly in trot.

It's got 4 girth straps to chose from, so could that make a difference?
My mum can't get time off to have a saddle fitter to come out until the end of term (6 weeks), so we're having a bit of a dilemma:

 

[meandmyself]

Which one fits best now? That's the one I'd use until I could get one prof. fitted.

 

[kizzywiz]

Sorry to sound horrible, but I wouldn't ride in any saddle unless I was sure it fitted, surely the saddle fitter could come on a Saturday, your mum can't work 24 hours a day 7 days a week!!

 

[Daphnelia]

I have to agree.