Woo wee you got yourself a handful! Nice job for stepping up and taking this animal in. First off, I agree a vet visit is definitely in order. If you can hear a whistling coming from him, an RI is most probably the cause. Tell us exactly how you have him set up. Temps, humidity, cage etc. I agree that setting up the snake in a quiet dark place will help him settle, just don't let his initial comfort take away from any urgency with taking him to the vet.