If you are experiencing loose stools and nausea while taking Clavulin for cellulitis, it is likely due to a common side effect of the antibiotic. One way to help lessen this side effect is to take the antibiotic with food. You may also consider taking probiotics to help with the diarrhea. It is important to stay hydrated and consider using a rehydration solution if needed. If your symptoms worsen or if you experience other concerning symptoms, such as cramps, fever, loss of appetite, foul-smelling stools, or blood/mucus in your stools, it is recommended to consult with a doctor as it could be a sign of a more serious infection.