Thanks for your post.
and gastrointestinal upset can be due to Allergies or Viral infections. Sneezing indicates something irritating upper airway passage and body wants to get rid of it by sneezing force.
Some times Gastroesophageal Reflux Disease
can also irritate upper airway passage causing sore throat
You should take plenty of water.
You may take over the counter ant allergic drugs.
Sort out what type of GIT upset you are having?
if symptoms persists or worsen then visit your doctor.
Hope it helps.