Painful but not itchy rashes, anyone have any ideas here?

I have painful burning rashes in my lower back, in my thigh and arms. I don't know what it is. First, I felt burning sensation in certain areas of my skin but when I looked at it, I couldn't see anything. There was nothing there. The next day these rashes started to come out in those painful areas, as seen in the photo. It is not itchy but it is painful when you touch them, like burns. I have these rashes now and I have other rashes growing in the other parts of my body. The old ones are starting to have blisters. I never have these before. I did not take any medication. Do guys have any idea what this is? I am not allergic to any food in relation to my skin.

I came from a hot and humid country then i moved to the US. I never had this before. I've been here for a month now and this only started 3 days ago and they are spreading first from my back in certain spots not all over my back though then to my thighs. I can see some rashes coming out from my arms. They have painful tingling sensation.