You're "Lucky 100" so let's working on finding something for you! If you can't find anything in the US on your ancestors, then you'll take the crown from me for slipperiest ancestors. Yes, your GF could have been going back and forth and missing the census years, but more likely it's bastardized spelling, or movements within the US. I'll friend you, message me, and I'll have a look.
If you haven't already done so, you should join the Lithuanian Genealogy group on Yahoo, pronto. Lots of knowledgeable members offering help...members mostly from US, some UK, a few LT. The link is on the main page of my GenealogyWise group. I'll catch u later to see what steps you've taken already, and what else you can do. Don't give up...I think you're in a much better boat than someone who doesn't know his real last name, or the village in LT...someone like, oh, me! I have a good feeling!