Acne and blemishes problem since 3 month

I never use to get pimples or blemishes. And i use to have very fair, smooth and glowy skin.One year before, i came to banglore from delhi There was change in food habit and environment. My skin starts getting tanned. I started using sunscreens TAC ayurdveda which is fine as it is really helpful in protecting the skin from sun damage. Though my skin is jot tanned anymore but now i am suffering from pimples and blemishes. Its around 3-5 months i have started getting pimples and blemishes over my cheeks.  I consulted a doctor and he said that i am suffering from acne and PIH problem. I am 33 years old now.  He prescribed some medicines: kojiglow gold  facelin and doxy 1 L-DR Forte capsule. I am under medication since 20 days but there is no change. Blemishes are still there and new pimples are also coming. Medicines are not showing any effect. I drink plenty of water and there is no change in food habit since one year. I have started using mamaearth salicylic acid with teatree  facewash