Any help would be great!?

my son is 10 weeks old and alot of the time during the day he is up for 5 or 6 hours at a time ..and when he acts sleeping..yawning...just very sleepy look...i try to put him down but he freaks out? any sugguestions..at night time he wil go to sleep around 930 or 10 for a 3 -5 hour stretch then wake every 2 hours or less to feed.. he is bed... any idea? i know he is getting over tired during the day..i try rocking him.. and sometimes i can get himto sleep in his bouncer if i bounce him..he always crys though at first ..how long is it ok for him to cry for?