I'm sorry to hear 'bout this. You situation does happen but for future reference, should you need hardwood floors installed at a later date, see to it that the installer leaves the wood in your house for about a week BEFORE he starts working. You would stack the strips/planks perpendicular to each other, one on top of the other. Kinka like how you'd build a hugh bond fire. (Lay a few in one direction then lay a few on top perpendicular, then lay a few on top perpendicular to that, and so on.) This way, the wood has a change to get acclimated to the conditions in the home. By stacking the wood, air and moisture can flow freely between the wood.
Other than that, like Henry said, don't fill the gaps. Check that the humidity level is 40%, give or take. You say it's 'normal' but you didn't say what it measured. (Some folks say normal is 30%; others say 60%.) Possibly going to 45% or a little more will help but no promises.