Your symptoms are suggestive of mucositis commonly seen with chemotherapy
Next Steps
you can use pantoprazole inj or tablet +sucralfate syrup 15 ml thrice a day. emeset is also helpful to alleviate vomitings. all these need to be continued for few days for optimal recovery. also get an advice from your doctor regarding any need to stop/reduce capecitabine.
Health Tips
don't stop capecitabine without informing your medical oncologist..