First off there is no way for you to know for sure if it is IBD, it could just be a respiratory infection and the snake is struggling to breath. There is no way for us to tell you what the exact problem is... That is why a vet visit is required.
Do you have a warm spot of 90-92F, and a cool side of 80-82F? If not the snake has probably become ill because it is too cold...
If the cage is not setup with these temperatures you should make it so immediately.