Sudden allergy

Patient: Hi, I had a dog for 13 years who shed with no problems whatsoever. A few months later, I now have a new dog and I am having allergy symptoms similar to my allergy with cats. Is it possible for me to have developed an allergy so fast? What can I do? Over the counter allergy meds do not work and I would prefer not to have to take allergy medication as I have never had an allergy to dogs my entire life.