Coping with Phantom Blood Trigger in PTSD

TW: blood/gore I have PTSD from a few trigger events from my time as a medic. My therapist said there's an underlying emotional theme of helplessness (they were bad situations) which is why they stick out for me, compared to all the things I've been through. My biggest trigger though is what I call "phantom blood", and I have no idea how to cope with it. I'll be going about my day, and I'm suddenly aware that my hands are covered in blood, and I can't get it off no matter what I try. It's so distressing, and I have to just cry, and shake, and run my hands under water or rub them in rough fabric until it eventually passes. Does anyone have similar experience and maybe advice, please?