Not just bread ...
Celiac disease is a very common disturbance caused by intolerance to gluten gluten is a protein complex contained in foods like bread, pasta, biscuits, etc.
Have the check-up offered by your CDC
to see whether your intestinal problems are caused by celiac disease
Anti-tissue Transglutaminase Antibodies IgA - tTG
Antiendomysial Antibody IgA
Immunoglobulin IgA
Blood count and Serum Iron
If the results are outside the acceptable range, contact your GP