Don't feel "dumb" about it at all. We Moms always have something we draw a "blank" on.
Some people use a frozen bagel. ??? I have never tried this myself. But, I know that gently rubbing their gums can sometimes help.
Maybe, is she sick or something? Often a baby is fussier when sick, and/or teething, or an ear problem? Perhaps just check with your Pediatrician to rule out anything else. He/she will look at her mouth.
But yes, she is mouthing everything, and this is usually because of teething. It seems you have tried a LOT of remedies... did you try the Hyland's teething tabs/drops? It's homeopathic and I used this with both my children.
My son liked to knaw on frozen things... and ANYTHING cold. I gave him crushed ice and he love that. Anytime he was teething, he'd want something frozen, and particularly ice.
If it is teething, they often will also get drooly too... and sometimes have runny poop. Have you looked at her gums? Teething pain can vary in length, sometimes its more than one tooth that is coming in, and each baby has their own "pain threshold." My first child, didn't even seem bothered with teething and did not have any discomfort. My second child, at around 6 months, started to get fussier at night and mouthed everything.
Also, around 6 months of age, they go through a growth spurt... at which time they get hungrier and may need to feed more and more frequently... .in addition to the increasing physical and cognitive changes.
Here is a link on teething:
http://www.google.com/search?q=remedies+for+teething+baby...
take care,
~Susan
www.cafepress.com/littlegoogoo