What Causes Red Rash On Stomach Spreading To Back After Nipple Piercing?

I am a 50 y.o. male. Recently I got a nipple piercing. 2 weeks after I had developed a red rash (not itchy at all) a crossed my stomach that has been slowly spreading on to my back. I have been performing proper cleaning of the piercing with mild antibacterial soap. The nipple is not sore or swollen or has I had any unusual discharge from it. Thinking it was a nickel reaction I had the piercer replace the surgical steel jewelry with Titanium jewelry. it's been five days but have seen no change. I have had no other changes in my life that I can think of so I'm not sure what is causing this reaction. my last physical was seven months ago and everything was normal. I don't really want to remove the piercing and I know my doctor, that's what he'll tell me. does anyone have any other advice?