How to put my infant to sleep???

my 3 month old used to sleep so well, now he doesnt sleep unless I am holding him. he falls asleep in my arms and only half of the time I can put him in his binet without him waking up right away. Anyways, he has night and day backwards, he sleeps almost all day and stays up all night. He used to not cry, but now its all the time at night. Im getting NO sleep and I dont like the whole, cry it out thing. Also, how much should he be eating? hes 10lbs and sometimes eats about 6oz and still seems hungry. I burp him a lot and give it time in between ounces, but an hour after hes eaten 6 oz, hes still crying despite all Ive done. I change him, rock him, give him his pacifier, play with him, take his temp. and hes fine. i cant call the doctor till tomarrow. I dont want to overfeed him... help??