First I would double check that the blade is put on correctly and isn't backwards. I would next contact Fiskars and ask for their help as they do stand ehind their products.
There are a few egonomic cutters for sale and I think you just have to try them and see/feel which is best for you.
I use Olfas with the straight yellow handle and never had a problem except when I put a new blade on incorrectly. - I wish I had one that was more ergonomic but I would rather spend $ on fabric right now.