Have you tried warming it to about 70F to see if that helps? If you do go the lager route, I would keep the temps up, your flavor profile is set, you're only trying to drive those last few points.
Was this an extract kit? DME or LME if so?
Something is always fermenting....
"It's Bahl Hornin'"
Kegged: Bourbon Barrel Imperial Stout
On Deck: German Lager