teething causes discomfort to some baby n they tend to be more cranky n dosent sleep well cos of the pain. you can ask your son's pediatrician for some teething cream to soothe his gums before bed/nap or give him teething toys to bite in the daytime if he is cranky. some baby dosent have any problems with teething though. some baby develope fever during teething as well. every baby is differnet. n some lost appetite. all these are normal.
make it a habit to clean his teeth after meals and before sleep with a damp hanky.