Hello,
I am sorry to hear about Lucky.
Honestly, the setup needs to be a little different. You mentioned that the rheastat turns off when the temperature turns 90. That is monitoring the ambient temps, correct?
They need a hot spot & a cool spot. The ambient temps when they reach higher than 83 or so they don't have anywhere to cool off. Do you have an air conditioning unit that helps keep it cooler in there?
She was awfully thin even if she was running around a week ago. She didn't get that thin in a week, so I think that based on the information yes, she had advanced metabolic bone disease. She did not have any UVB lighting, & they can only go for so long until their body begins to deteriorate.
If you are going to continue to keep your other one in the shed, it needs to have more specific lighting & the temps should be 95-110 on a certain basking spot & 78-82 for a cooler spot. At a 6 foot clearance, you could request the Zoo Megaray which reaches up to 6 feet I believe instead of the regular 100 watt Megaray. You will need to call Bob Mac as he will want to speak with you in regards to how to set it up etc before he sends it out because it is a much stronger light than the conventional ones are.
Let us know if you need more help.
Tracie