Thanks for writing in.
As you have changed your house 4 months back, hives
are unlikely due to new house.
As per your history, it looks like that culprit is laundry powder. Though you have changed it back to old one; hives are still there. So wash cloths twice and iron it properly.
lotion over hives and take cetrizine
tablet 10 mg - once a day. [children- 5 mg once a day]
Take medicine for 5 days and lotion for 1 week. Problem will resolve.
Wish you good health.