Is it food allergy or bugs bites?

Hi, I'm from Indonesia and apparently I'm having this itchy large red rashes on my skin. It has been three days and still itchy. The rashes don't spread out much it's just in my both arms and (just a little) my stomach. The first day when it appeared I had a nausea. Could this be caused by what I'm eating or just some fleas/bugs bites?