My tort had this. It was the prickly pear cactus fruit I fed him. Go ahead and get him tested, but think carefully if you fed him anything that would have caused that. Good luck!
“Glochids or glochidia (singular "glochidium") are hair- like spines or short prickles, generally barbed, found on the areoles of cacti in the sub-family Opuntioideae.”
Welcome. Your little guy is adorable.
I hate to say it, but you will likely need to separate your torts at some point. My two Greeks lived together happily - until one started ramming, biting (causing bleeding), and generally making life horrible for the other. My profile pic was the closest...
I remember with halogen lamps, you couldn't touch the bulb with bare hands, cause the oils would cause the bulb to fail. When you replace it, try using a towel to screw it in?
I have two Greeks - they cannot be in the same place for more than 30 seconds before one starts biting and ramming the other DO NOT by two, unless you have the room to have two totally separate enclosures.
The mixing tub works great. Keep the substrait moist - mixing in coco coir may help - and humidity should be ok.
As for temps, you'll need to get the MVB higher than the level of the lip of the tub. I suggest either getting a lamp stand or building something, but make it sturdy.