I'm sorry that your question wasn't answered in a timely manner. Please let me know if you still need help. This is a difficult question to answer directly because Cashew symptoms of lethargy and not defecating while important aren't pathognomonic for any one particular disorder. Is he not defecating because he hasn't been eating? To determine the urgency of having him attended to by his vet please check his vital signs for me...
1) Check his gum and tongue color. They should be nicely pink - not whitish (anemia) or bluish/greyish (cyanosis/hypoxia/lack of oxygen to his tissues).
2) Check his respiratory rate at rest. He should be taking less than 30 breaths/minute while asleep or at rest.
3) Take his rectal temperature. Any body thermometer will do when placed 1.5" into his rectum for 1 minute. Normal is 100.5-102.5F. This is a two person job!
Please let me know what you find.
Have any new symptoms arisen? Sneezing, coughing, nasal discharge, regurgitation/vomiting, swollen abdomen, drinking more than usual, difficult urinating or urinating a higher volume of urine than usual, or lameness, e.g?