The speaker is sitting somewhere they shouldn't be listening to music, or at least feeling it, and the song swallows them. "Lost and buried" is a strong way to describe being absorbed by a tune, and it suggests something closer to sinking than to enjoying. The music is "not fit for the office," so it seems to clash with the speaker's working, respectable life. Country songs are often about hardship, and here the tune seems to carry that world right into the speaker's head.
The second stanza turns personal. The song "tells me of debts and illness," as if it were speaking directly to the speaker's own worries. The swelling gut is the most striking image. It could be literal sickness or a stand-in for dread, and either way it can't be hidden: it grows "beyond any secret." The mood is quiet, weary and a little anxious. The speaker doesn't shout or explain, and the plain, short lines make the sadness feel all the more honest.