Rash / sores around upper thigh

Hello,

In the last couple of weeks I noticed a couple of big red spots - what I thought were insect bites (I'm living in Japan, there are plenty of weird things around I guess)

They were extremely itchy, but I figured they would go away. A few days later I noticed some similar ones had also appeared on my foot:



These ones though have disappeared, and my foot looks normal. However, the ones which appeared on my inner thigh are only getting worse, I'm wondering if I've had some sort of reaction to them. Pictures I just took:




They are odd in that they appear fairly white in the middle, but with a red ring. Originally there were only two or three marks, but there seems to be more now......making me think perhaps its not a bite.

Anyone seen anything like this before? Any help would be appreciated...

Thanks