Having rash on right arm, allergic reaction on inner forearms, itching and burning sensation. Prescribed steroid creams and antihistamines. Remedy?

Rash on right inner arm for 4 weeks since trimming agapanthus. Got a small scratch and lots of sticky sap. Eyes and right breast were involved but antibiotics from my doctor cleared it all for a few days. Steroid creams and antihistamines did not seem to help. Now it has spread again around inner elbow - red welts, itching, burning, slight stinging and sometimes crawling of the skin. Difficulty sleeping. I always get allergic reactions on inner forearms when I garden and suffer from continual sinus allergies. Need some anti-itching remedies use or suggest to my doctor. It may not be agapanthus and our cat now coincidentally has stomach discomfort every evening. Thanks