Thank you for posting your query on DoctorSpring.com.
It seems like you have an allergy. It would be best to apply a stronger potency glucocorticoid other than cortisone.
A cream like Mometasone, applied just once a day will be helpful. You will need a prescription for this.
The allergy may be due to any irritating factor,most likely the new detergent.
In case of itching, you could take Tab. Claritin 10 mg, once at night, for 5 days.
Please let me know if you have any queries.