3 month old baby won't sleep alone during day?

My 3month old son will not sleep durin the day the only way he'll sleep is in bed with me. At night time from 7pm till 10;30pm he wil only sleep with me but from his last feed at 10 30 he will settle himself and sleep till 7am for a feed and again will settle back down till 10am when he gets up but any other naps he will not settle without me I've tried letting him cry I've tried takin him for walks nothin works except in bed with me. Anyone else have this problem? Any ideas?