I've had these for a few months, they are flat and do not itch or hurt, the only difference is they are red/pink coloured patches. I also have one on my chest, and one the other side of my neck (just single patches though, not like the 5 here)
I thought maybe allergy, but nothing has changed in my lifestyle. I was taking hayfever tablets (loratadine) in the summer but that did not affect it