Sometimes those noises can be scarry. Most likely the dr. could also hear good breath sounds along with the other gunky noises. Do you really think it's in her lungs? Many times in the peds, loud sounds that we think are in the lungs are actually in the upper air ways. Put your hands on her chest when she's breathing. Can you feel the rattling in her chest as well.
Honestly, it sounds like she needs a good breathing treatment to me. Is she calm and relaxed or is she breathing fast and heavily? Does she seem anxious? Are her lips and finger tips a nice pink color and blanchable?
If it were me, I would watch my child for signs of getting worse. If she's not better though after several days, then I would visit the doctor again. You might need another opinion.