spider bites?

egoldst1

Do spider bites really come in threes? LO has three pretty good sized red bumps on his rear end... they curve in a line... each one getting smaller. He also has some very fine red bumps on his upper back, only slightly raised. Any ideas?

egoldst1

Here is a picture. This is on his right butt cheek! He's got one more red bump higher on his back.