Been there, done that! Have 4 boys and worked part time and still had this happen!
Make sure you are rocking him in his bedroom. Make sure lights are low or off (off if possible). Try some soothing music too. Rock him close and tight to you (head on your chest is good - so he can hear your heartbeat. Do this until his start getting heavy. Lie him in his bead. If he stands up, lie him back down and tell him it is bed time. You might have to use force. (I know it is hard. I could not do it with the first 2, but by the last 2, I realized it for their own good.)
Once he is down, rub his back lightly. If lightly does not work, then try firmer pressure. He will fall asleep happier this way than if you made him "cry it out." If it hurts you to put your child down screaming and let him scream for 20 minutes then do not! You will feel it later! ;) This might take awhile; it might take weeks, but you are teaching your son something- to fall asleep on his own!
Email me if you need more help! Good luck