It could be an obstruction or gas. To rule out the first thing, it is necessary to take it to the veterinarian for an X-ray to confirm that there is nothing obstructed in the digestive system or intestines. If you confirm that this is not the case and that it is gas, the veterinarian can give us simethicone that will help you to expel them and also some medication to make the digestive system start up again. In addition, it is important to remember that you will also need a pain reliever. They also do very soft massages in the belly in a circular direction and apply heat (without burning), as well as small massages in the area around the anus to stimulate it to poop. It is important that they are hydrated and that is why we will give them water with a syringe if they are not drinking them alone. And of course it is very important that they eat, to help the bowel move, if necessary we will do it manually. Gases are very painful for guinea pigs, and they put their lives in danger, so it is necessary to treat them immediately if necessary.