Greetings.
This appearance is suggestive of an allergic reaction. The trigger could be a soap, perfume, a new medication, any chemical , a new body lotion and so on. It may be difficult to find the root cause but the good point is that it can be treated effectively.
Next Steps
Meet a Dermatologist.
Health Tips
Initiate OTC anti-allergic tablet and a soothing dermocalm lotion( on affected areas) till you visit a Dermatologist.