My Husbands Symptoms Are Upset Stomach, Dizziness, Tiredness. He Did

my husbands symptoms are upset stomach, dizziness, tiredness. He did have a bout with Verdogo about a mouth ago and it as passed but once in a while he feels like it is coming back only but does not come back fully. He is usually a strong man, age 73, and does not lay down during the day. Can you help? Also after meals his stomach is upset. These are new complaints.
Thank you,
Roseann Irvin