I have red marks on both of my cheeks for the last one week, What could be the reason ?

We would need more information. What has changed in your life? Meds, diet, sleep, stress? Do you have any conditions? Take an meds?

What kind of red marks are they? Are they bruises or just a rash?

My Office is having airconditioner but due to my nature of work have to go out in a heat many times a day and outside temperature is plus 45C. Last week it was almost touching 50C. Kindly note I'm not exposed to sun but heat.