First the obvious ~ Have you changed anything at all? Shampoo? Hand Soap? Clothing detergent? If the itching keeps coming back diagnosing the issue as "stress" is probably too broad.
Keep a notebook of absolutely every single bite of food you take, what time of day, etc. You may think you are not eating something different, but think very carefully about where you buy produce, etc. if you have changed brands of something basic like a chicken broth. There can be one single ingredient that causes allergic reactions and you are simply not aware of what it is yet.
Also have you vacuumed thoroughly, washed sheets, etc.
Allergies are such a drag and often very mysterious.
Good luck. I hope you can figure this out and get some relief.