My 6 month old has plummeted down the weight chart

Patient: My 6 month old has plummeted down the weight chart (76% at 1m, 44% at 2m, 25% at 4m, 8% at 6m). Her doctor said she’s completely fine because she hasn’t lost any physical weight (gained one pound since 4m). Am I worrying unnecessarily or should I get a second opinion?

Doctor: