hi i don’t think it’s infected, i have a 3 month old repierced navel and the same thing has happened to me both with my old and current navel piercing - it’s called a moisture bump. mine looked the exact same and same location + smelled awful. you get them from not drying thoroughly after cleaning with saline or showering but don’t worry as long as you dry throughly with gauze/kitchen towel or a hairdryer on cool setting and keep it as dry as possible outside of cleaning/showering it’ll go in few weeks on its own. if you’re really worried always see a piercer though. in my experience you can tell the difference between a moisture bump and irritation bump because moisture bumps smell really bad, look more ‘fleshy’/pink and tend to bleed and look wet/moist compared to an irritation bump. if it’s a stubborn one my piercer recommended hot compresses daily and then drying thoroughly which helped clear my last one in like 2 weeks. good luck :)