What Causes Itchy Blisters On Abdomen, Backside Of Thighs And Buttocks?

I had these little red bumps going down the right side of my stomach. They re in a line and each little cluster has about 3 or 4 little separate bumps. they itch really bad sometimes. They don t hurt to the touch. They mainly itch at night and have woken me up from my sleep a couple times. There s a long one going across my butt. I can t tell if its just one giant one or a bunch of clusters. I have a few bumps on my left side of my stomach and I also have a few bumps on the backside of thighs. What could this be? I can provide pictures if necessary.