Shortness of breath or wheezing after eating may be due to a variety of heart and lung problems, or to gastroesophageal reflux (heartburn). It may also be a symptom of a severe food allergy reaction called anaphylaxis.
Shortness of breath after eating may be a first symptom of anaphylaxis, and will develop within minutes to two hours after eating. Difficulty breathing and swollen lips or hives means that it's very likely you are experiencing anaphylaxis.
However, some people who are experiencing anaphylaxis may only have breathing symptoms. They may feel like they are having an asthma attack.
If you recently ate, have known food allergies, and are feeling like you are having a severe asthma attack, use your epinephrine auto-injector (Epi-Pen or Twinject). You may or may not be experiencing anaphylaxis –- but your auto-injector will stop both anaphylaxis and an asthma attack. Your inhaler will not help if the problem is anaphylaxis.
After using your auto-injector, lie down and have someone call 911. You will need to be monitored by a doctor for potential further reactions.
If you do not have known food allergies, but are experiencing difficulty breathing, seek emergency medical care.
Waiting to see if you are experiencing anaphylaxis may mean it is too late.
Sources:
Food Allergy and Anaphylaxis Network. Anaphylaxis. Accessed 1/16/2011. http://www.foodallergy.org/section/a
NIAID-Sponsored Expert Panel. Guidelines for the Diagnosis and Management of Food Allergy in the United States. The Journal of Allergy and Clinical Immunology. Volume 126, Issue 6, Supplement, Pages S1-S58, December 2010
McCartney, Anna. When Anaphylaxis Looks Like Asthma [PDF]. Allergy and Asthma Today, Winter 2007.

