Why does my 5 week old babys pee smell like penicillin?

Is baby on a med ? Many medications are removed from the body through the urine. Certainly, ingested or injected antibiotics like ampicillin, amoxacillin & similar meds can cause a noticable urine odor. If baby is on no meds, this may indicate a metabolic issue & should be reported to the kids dr.
See below. Penicillins are eliminated via your infant's kidneys concentrating in the urine. The urine will smell just like the pills…medicinal and bitter moldy smell.