Go with your instinct. You and your husband are the only advict for your child.
When my daughter was 6 months old we noticed her left eye was not keeping track with her right eye, she was crawling in to objects and screamed whenever we covered up her other eye. When we took her in for her 6 months shots we were told that nothing was wrong the doctor would check her again and the next visit.
We were concerned so we called the eye doctor who fit us in immediately and sent us to a specialist the very next day. Turns out our little girl had a rare form of cancer, retinoblastoma, had we waited it would have traveled directly to her brain. A week laster the tumor and the eye were removed.
In our visits to St. Jude Children's Hospital I have met a number of parents who's stories are similar. The doctor missed the diagnoses and had they not received second opinions or been persistent the children would not have survived.
I am not writing this to frighten you. I am only saying always follow your gut when it comes to your child. Doctors see hundreds of children, are not familiar with every disease out there, and are not with your child every day.