The Lavaquick MSDS lists the Lavaquick main ingredients as:
(EDTA) Ethylene Diamine tetraacetic acid, tetra sodium salt (a chelating - water conditioning agent)
In other words, Lavaquick is a garden variety wash aid. It should not stain your prints unless it (or your water) is contaminated with a staining agent.
Try fixing your prints in 2 baths of fresh fixer followed by washing in several complete water changes - forget the Lavaquick.
If your prints are still stained or fogged - check the paper for fogging and your developer for contamination.