Try to figure out the cause for your itching. It could be high protein consumption, dust,pollens, insect bites cold or hot temperature etc .once you eliminate the trigger you will get lasting response. Read about Urticaria it might help you in knowing the causes so that you can eliminate the trigger.
Next Steps
Calamine lotion can be used for the rashes . It gives soothing for immediate relief.
Health Tips
If it doesn't help, consult a dermatalogist with the pics showing the rashes for definitive Diagnosis.