help!

My LO is now 3 months old.  From the time he was a little over a month he is so difficult to put down for a nap.  It seems to have started when he became more aware of things.  He's very active and alert throughout the day.  When he shows signs of being sleepy and I try to hold him to get him to sleep, he starts to cry hysterically.  The second he thinks you are trying to get him to sleep, he does this.  He sleeps so well at night though, thank goodness.  I think he just is so tired from the day and somehow his body knows it's nighttime becAuse he has never done this at night.  It's so frustrating and I feel helpless when he gets so worked up.  He's too young for cry it out, even if I chose to do that method and he gets like this before you even put him in his crib.  It's actually getting him to relax that is the problem.  Anyone have something like this with their LOs?  Please help if you can!