What does a stress rash usually look like?

Variable. Skin rashes from stress can come in any form. If you suspect this is the case, see your dermatologist for proper evaluation and treatment.
Swelling. Stress can sometimes lead to hives. It can also cause flushing or even itching and redness. This would be similar to acute trigger for migraines, or other conditions which acute emotions can trigger.Chronic stress is less likely to cause these kinds of rashes.