Hello iam 29 years man and i sm suffering from flu. i noticed little bulge in my lymph node in the neck of left side(under msndible) is it normal?

Yes...: When you are sick (such as the viral illness you are describing as flu) it is normal to have enlargements of your lymph nodes. You can expect that as you feel better, the node will slowly return to normal. If the large node persists beyond a few weeks or seems to be getting larger, have it evaluated to confirm that there are no secondary problems.

Lymph node: Yes, it is normal to have an enlarged lymph node under the mandible when you have the flu. The lymph nodes enlarge near the site(s) of infection while they are producing more white blood cells to fight the infection. In this case, enlargement is a healthy sign of a good immune response. It may take weeks for the lymph node swelling to resolve, so don't expect it to disappear immediately.