Hello and hope you are doing well.
You could be suffering from chronic urticaria. If the allergic rash lasts for more than six weeks it is called chronic urticaria. There could be many triggering factors. On exposure to the allergen, an Immunologic (IgE) or a non-immunologic reaction is set in process, which ultimately releases histamine, which acts at the peripheral receptors, resulting in allergic reactions and rashes.
The aim of the therapy is identification and removal of trigger factor. It is the most important and the only effective long-term therapy. An allergy specialist can help identify the allergens and desensitize you.
If there is accompanying swelling, redness, discharge and fever it is most probably infected. You may need to consult your primary care physician who will examine you and initiate appropriate therapy.
Hope this helped and do keep us posted.