Voltarin is non steroidal anti inflm which can cause severe gastric inflammation
especially with background history of Barrett's oesophagitis - you are more likely to have NSAID
related gastric side effects
Voltarin should be stopped immediately.
Also given the fact that you had gastroenteritis
recently - you gut lining has become very delicate and any irritant will cause upset.
You must consult a Dr who needs to examine your abdomen & rule out possibility of ulcer / rupture & if that is the case surgeons needs to intervene.
Hope this helps