I think as soon as you get it cleaned up give it a good soak in cool fresh water to lift all those multiple chemicals you've tried, as well as the Oxyclean, out of the overall quilt, and maybe rinse again. Spot rinsing is good while you are working on it, but I'd want to know the chemicals are out of the fabric in case any of them could break the fabric down over time.
Oxyclean has saved me several times from having to throw away some clothing that nothing else would save. I soaked a pair of khakis once for about 48 hours, changing the solution and rubbing several time until Oxy got the stain out...but then the pants got a good wash and rinse.