All over body red rash with no bumps or raised welts. Slightly itchy, more of a tingling sensation, warm to the touch. Started forming at the head and working down the body to lower extremities. Has happened 3x in 2 weeks, only lasting for a few minutes. This last time, over and hour and no sign of letting up.

Sounds like hives, which can be caused by an allergic reaction. Been there done that.

What it is you're allergic to, you've obviously been exposed twice, since you've had this reaction twice.

You will need to see a doctor about the rash, but very unlikely you'll find out what caused it, it's not that easy.

Think through your week, what you've eaten, if anything in the household has changed (soap, laundry detergent, shampoo, hairspray, cream, makeup, etc. etc.). Start eliminating things you haven't used before, they're likely the cause if this is the first time this has happened.

But do see a doctor to confirm that it's an allergic reaction. It could be something else as well.