It is reassuring if your child has a period of being well between each episode and if he is not having any complications from his colds, like ear infections, sinus infections, pneumonia, or asthma.
Ear infections are very common and often occur with or after a cold. Boys get them more often than girls do, and over 75 percent of all children have at least one. Two or three ear infections a year is not an excessive number, and they usually become less frequent as children get older. Assuming your child is having uncomplicated ear infections that resolve readily with appropriate treatment, I would not be alarmed.