2 yo developed redness, blotchy, and hives on tops of hands and feet,face,arms yesterday. all of these keep appearing and going away and appear 2days?

Hives: Very characteristic for hives to appear, resolve and reappear. Hives can be due to a variety of reasons including food, personal care products such as perfumed/dyed soaps or lotions, or infection. Needs urgent medical attention if also swelling of lips, tongue or drooling. Otherwise followup with your child's doctor if symptoms persist more than 2 days.

Various causes: Recurrent hives in a 2 y/o is most commonly a associated with viral infections. Another possibility would be a newly developed food allergy or an allergy to the Prilosec. Try giving a ½ tsp of Cetirizine twice a day for a week then stop it and observe. If it returns then look at the above mentioned factors and restart the anti histamine and maintain it for 4,weeks. If it returns then it's Chronic