I have not heard of this particular medication, but just went through something similar. I was prescribed an anti anxiety medication for post partum depression. The prescribing Dr. (a physciatrist) was confident it was fine to use. The pharmacist told me it was not recommended while breast feeding, and my son's pediatrician also recommended not to be on it while breastfeeding. I opted to stop nursing at 4 months as I was responding well to the medication and it was very important I be on it.
I would get a second opinion, and also talk to the pharmacist (they are, in my opinion) the best source of information on medication..after all, it's what they do for a living. Then you will have to weigh the information and come to your own conclusion. Make sure you have a list of all possible and likely side effects for the baby.
Good luck to you!
THere are other painkillers that are compatible with breastfeeding. Your pharmacist would be the best one to tell you about this. Then get your doctor to prescribe appropriately.