I would be very concerned that he has an intestinal blockage that has been caused by eating the cloth. This will prevent food and fecal matter from moving through the intestines. You need to seek immediate vet care to have him checked. Shaking is often a response to pain. This is now urgent because of the pain that you are seeing.
The vet will probably do a physical exam and maybe an x-ray to rule this out (or in!) and neither is very expensive.
Let me know if you still have specific questions about this. I fear that my answer is too vague.
