Hi and welcome
Please check the front teeth whether they are still sitting firmly in the gum or whether they are wobbly They are about 4 cm long (the roots are just in fron of the grinding premolars and molar teeth at the back. Because of the length, breaks can happen anwhere.
Your vet may also check whether your piggy may have otherwise injured their mouth or spine; especially if they are not eating quite normally. Keep in mind that three quarters of the daily food intake is hard hay, which you cannot control by eye.
Guinea pigs are prey animals who feel especially exposed right out in the open. They should never be put on a table top in case of blind freak jumps; the risk of accidents is just too high.
More about how prey animal instincts work and what you can do to avoid triggering them as much as possible:
Understanding Prey Animal Instincts, Guinea Pig Whispering and Cuddling Tips
How To Pick Up And Weigh Your Guinea Pigs Safely (videos)