This is not a silly question at all! It turns out that allergies to metal are very common and the symptoms that you describe are in fact quite consistent with an allergy. Skin under a ring can sometimes become irritated just from friction and moisture; however, contact dermatitis, which is the allergic reaction, is also very common and it is hard to differentiate the two without having it checked out by your doctor
Most people are not allergic to gold but, rather, to nickel which is a common metal that is added to many gold rings. Nickel allergy is the most common type of metal allergy in the world.
I would suggest that you not wear your wedding ring until you have the area checked out by your doctor. If it turns out to be an allergy, continuing to wear the ring will make things worse. You could also try some over the counter hydrocortisone cream on the area while you are waiting to see your doctor.
Metal allergies can develop at any point during life. Therefore, even though you have been wearing the ring without problems for a long time, it is entirely possible that you have now developed an allergy.