Hello Thank You for contacting HCM. You need to observe that after what specific things does sneezing occurs. This will tell you that you are allergic to what specific thing and then try to avoid it. If its soap then change brand. Acne usually occurs on face. What you have on back could be miliaria but that needs a dermatological examination to confirm it. Treatment for it will be given by dermatologist after examination. If its miliaria then its main cause is hot weather. For recurrent allergy i would suggest you to take montelukast one daily for one month. Research has shown that it decreases the allergic symptoms considerably. Hope this answers your question. If you have additional questions or follow up questions then please do not hesitate in writing to us. Wishing you good health.