Weird rash on nipple?

I covered as much as I can but kept enough so it can show placement. I went to doctor a few months ago for an annual, and they said they didn’t feel anything when I had expressed my boyfriend thought he felt a lump. Within days of leaving, I started to get this rash, it started out much smaller and it’s been getting bigger and itchy and slightly painful. It’s no where else on my body, just on my nipple. I’ve tried changing detergents, bought new bras, tried anti-itch cream, allergy meds, and nothings working. The soonest I can get back in is in 3 weeks. Does anyone have any idea of what this could be, or how I can relieve the itchiness? By the way, I haven’t been itching it at all in hopes that it would go away