I bought a house a few months ago and its driving me crazy. The entire house is loud, wakes anyone and everyone up if someone even walks down the hallway, and is especially loud in the basement where my son sleeps. Things I've tried:

Searching for any gaps between the subflooring and the joists to insert a wedge and glue. Nope.

Used the decapitating screws from the upstairs down into the joists, dozens of them in a single area, nope still squeaks.

Used fine granite powder to lubricate between each floorboard. Nope.

Looked for any nails sticking out from the basement ceiling and hammer them sideways. Nope.

Drilled a hole to search for an air gap between the hardwood and subfloor to pump in an expanding adhesive. Nope, the hardwood is flush to the subfloor. There is no gap.

I'm out of ideas.

At this point it seems to just replace the entire floor. I'd like to sell this house in 2 years or so and get something larger for when we have another baby, but it seems to not be worth the expense vs gain in value.

Thoughts?

Edit: I think I'll call someone to come look and give me a quote on new floors. You all have been amazing in helping me!