I wouldn't worry just yet either. These animals can go a very long time without eating, even the young ones. I usually like to give my boas a hot spot of about 86-88 but 90 isn't too hot as long as they have a cooler area. How are you thawing and presenting the prey and how often are you attempting to feed? Could the animal be preparing to shed? I'd keep offering food every 10-14 days until she starts to eat again. You may have to leave the prey in overnight if she doesn't take it from the tongs. If she hits the 12 week mark I'd try a live prey item. Keep us posted on your progress please.