are red, itching blotches that appear on the skin, usually as you suspect in response to an allergic or other sensitizing trigger. For example, although hives are very common with food allergies, as you mention, they can also be caused by other triggers, such as a recent viral infection. Also, a number of medication sensitivities or allergies can cause hives.
I suggest that you get in to see your primary care doctor
about this issue. They will be able to help you review any potential recent exposures (such as a virus, medication, new laundry detergent, etc) to see if an offending agent can be identified. They can also give you suggestions about what medications you can take to relieve the itching if the hives recur.
Occasionally, hives can be a sign of a serious allergic reaction that requires emergency medical attention. In particular, if you notice any swelling of the face, lips or tongue, or if you have any trouble swallowing or breathing, you need to seek immediate medical help in an emergency room, as these, together with the hives, may be signs of a life threatening allergic reaction known as anaphylaxis.
Assuming you do not have any of these serious symptoms, you can just make the appointment with your primary care doctor at your earliest convenience.