Rash on breast

Omg it’s getting worse!! I stopped breastfeeding about 3-4 weeks ago and I’ve only been pumping. This rash started about 3 days ago and it’s getting worse. I just put some hydrocortisone cream on it and it helped dramatically. It’s just my breast that’s itchy, not my nipples. Actually it’s in both breasts but this side is worse..

But any ideas on what it could be? I’d like to go to urgent care bc of how much the rash has spread but I lost my insurance on the first.. perfect timing. I do have sensitive skin. But I haven’t changed any skin products or anything like that.. I wash and sanitize my pump stuff on a regular basis. Make sure my hands are clean while pumping. ??