I didn't develop allergies until I hit my 20's. Now that I am in my 20's I have a lot of allergies. I take Zyrtec every day now just so I can take a shower without breaking out in hives. And that's even after filtering the water. It's entirely possible that you are getting allergies now that you never had before. Don't scratch your hives and put Caladryl with Cortizone over it on it. It's the best home remedy I found.
Hi
Welcome to the forum!
Based entirely on your symptoms, this looks like urticaria or hives. The swellings or wheals produced after itching can be pale (of skin color) or red. Urticaria is usually triggered by allergens, such as drugs, foods, insect bites, inhaled substances, in response to sunlight, cold, heat, stress, exercise, or a viral infection. Other common allergens are pollen, mold, dust, pet dander, or cosmetics. Since you experienced an itch, just go over these possibilities in your mind. Something may strike you. You may be able to pinpoint what causes it or you may to have to go for allergy testing.
Hope this helps. It is difficult to comment beyond this at this stage. Do consult your doctor. Please let me know if there is any thing else and do keep me posted. Take care!