My baby has a swollen lymph nodes with no fever , pain  and the nurse practitioner told us if it don't go away in a week goto a pediatrician?

those are not uncommon.  i currently have one on my neck after i was dealing with a sinus infection.  just keep an eye on it.  if your baby is still swallowing and eating fine, i wouldn't worry about.  it should go away on it's own within a week.  if it gets bigger, then you go back.

A nurse practitioner?  If it were my baby I wouldn't rest until an MD had examined him or her.  Don't wait, do it asap!!

Where did the three months come in? Has it been three months since you took the baby to the doctor, or one week?

If the NP said to go back in one week if it has not resolved, then go back in. I would even go in if it seems better just to confirm. Did they do any blood work? If not, you should get that done. Go back to the doctor as directed.