Spiders are pretty weird animals, so the lying upside down, blowing bubbles, etc isn't all that weird with that gene. Even if she doesn't wobble too bad, those are both fairly common with the neurological abnormalities that go with being a Spider. I wouldn't worry too much unless you see it getting significantly more severe. Same with the yawning and sneezing, if that gets worse, definitely get a,second opinion-- I live in PA and I love my vet, so if you wanted a second opinion, I can refer you.