We recently got prefininshed bamboo hardwood flooring installed in March. When it was installed not every row of the flooring was nailed, only every other row was nailed. Now I think the floor is expanding and the rows that were not nailed are starting to raise in certain areas. So when you step on that area its like a bubble and it goes down and up as you apply and release pressure. How can we fix this without having to put nails in the areas where there are bubbles.