Random Spots on Stomach

Sydney
I've been getting these random red spots only on my stomach, chest and back. It's been happening randomly but not too often. My sister said it looks like a hive breakout because she's gotten hives before and knows what they look like, but these don't itch at all! So that makes her think it's not hives. 
I've been trying to pay attention to if they appear when I use a certain body wash, if I wear certain clothes, and things like that. And it can't be my laundry detergent because then I would always have them, I wash my clothes in the same detergent all the time. I can't seem to find anything that can be the cause because it's so random! 
I don't have bedbugs, I've checked all around my bed and wash my sheets a good amount. 
They usually disappear in a day or two and don't come back for about a month. They honestly don't cause any discomfort at all, it's just really weird and I want to know what it is. 
Does anyone have an idea of what this possibly could be?!
The flash makes the hair on my stomach more noticeable 🙈 haha