You will need to contact a vet down there in South Africa and have them look at the teeth. Find a vet that has seen chins if you can. Could be something stuck in the teeth. Could be spurs sticking out the side into the cheek or tongue area. It's important to get the chin into the vets office and be seen. If the animal is not eating properly on the teeth it can lead to more serious problems. Such as loss of weight, not eating due to pain, sores around the cheek area or tongue. Other teeth not being used properly. Possible infection.
Several years ago I had a chin who was pawing at the mouth. Took her to the vet and the vet looked inside the mouth. Couldn't see anything. So she suggested having Sunni come back to be anesthetized and have a closer look. The vet also allowed for a possible surgery to grind the teeth if needed. Indeed the vet did find a tooth spur. It was ground off and it never came back during her lifetime.
Best of luck. And return to this post with an update. Updates can be such a great learning tool to the rest of us reading.