I Have Self-harm Scars On My Wrists, About A Year

I have self-harm scars on my wrists, about a year healed by now but for the past few weeks they have been itching like mad. There's a rash made of small bumps that become red and inflamed if I scratch but even if I leave it alone there are still bumps on the scars themselves and all around the area. I've tried baby lotion, coconut oil, hydrocortisone cream, and taking oral antihistamines. What are some possible causes, and what could I try to make it stop?