Hello there, It is true that with age your immunity does go down but there are ways that you can delay its degradation. 1) Please get yourself evaluated for Fasting and post prandial blood glucose. If you are an undiagnosed diabetic then the raised blood sugar levels in turn contribute to higher rate of infection. 2) Have a balanced diet with protein rich food like dals, soya, milk(if vegetarian) and Eggs,chicken, fish if you are non vegetarian. 3) Also have plenty of fresh fruits and vegetables in your diet and if that is not possible have a multivitamin once in 3 days . 4) Find 1 hour everyday for physical activity(brisk walking, jogging, swimming). the Increased blood flow during exercise helps to kickstart your immunity by making the body handle stress better. 5) Itching in armpits and groin may be signs of fungal infection. Wash these areas with soap and water and wear dry clothing that is non-synthetic as synthetic garments promote growth of fungi. I hope these help you. Kindly get back to me if you have any further queries. Dr Arun A