1 year old always not well

Since he was born he would alway get the cold it would last for weeks he would get better for a few days the he has it again. He always been sick. Keep taken him to the doctors and they are not worried as its just a simple cold but he always has it. He has a bad cough and a runnynose all the time I feel bad for him as he has trouble sleeping as he has trouble breathing with the blocked nose is there anything I can do to stop I'm catching everything