It is good of you to be concerned for this baby, but rest assured that it is very highly unlikely that the baby would have been harmed by the relatively transient exposure to your exhaust fumes. It is much more likely that you would be harmed by either of the two pollutants you mention. That you were able to send this E-mail is evidence that you did avoid CO intoxication, even from the toxic levels you describe. Your blood level, if elevated, would have returned to normal, long before your receipt of this message.
The hydrocarbon content, or what is often referred to as Particulate, exposure, if causing harm (asthma or bronchitis) would have done so with the onset of cough and/or shortness of breath occurring within 24-48 hours of the exposure.
If the potentially harmful exhaust is directly from combustion, rather from a leak in your exhaust pipe that could be repaired, you must get rid of the car and not give or sell it to another person who would then be at high risk.
Good luck
Sorry - additional detail I missed out - the fumes could have let out upto 9 or10 time the allowed amount of CO (Carbon monoxide?) and three times the allowed HC (I think this may be hydrocarban content?).