Red, Itchy Bumps On Shoulders, Elbow, Arm. Not Caused By Clothes. Could It Be Food Allergy?

About a week ago, a cluster of red, itchy bumps appeared on my shoulders. I thought I might possibly be allergic to the sweaters I was wearing, or the chemicals on them, but after washing all of them, and not wearing them for a few days, another cluster appeared on my right arm near the crease of my elbow. The bumps are still on my shoulders and are more prominent on my left shoulder (always have been), and they are now on my right arm. I am concerned that this could be an allergic reaction to something I am eating, especially since my mother has food allergies, many of which did not appear until she was in college (as I am now).