I assume temp and humidity is still high? Has he eaten any large meals lately? My Fantasy will completely 100% burrow herself after a large meal (a mouse/3 Hornworms) for a few days and only pop up for the next feeding. Then when she gets it, its back under til the next.
Im also wondering if the test was a false negative. Just because the worms didnt show up in the sample, id be hesitant to call Orion 100% parasite free just yet. Im just firing shots in the dark at this point tho. For better answers, copy and paste Griffs trouble in the enclosure sticky with the questions answered.