Feeling Fustrated

I just don't know what to do. I have an otherwise perfectly content baby during the day, and at night, all hell breaks loose. I honestly feel like I don't know what I am doing with Simon, and the screaming that he does...I just don't know if I can handle it any longer. I really feel like flying off the handle sometimes! At night, he has a quick little cat nap at around 6:30, and I give him a bath at around 7-7:15, give him a bottle around 7:30, and you would think that he would be sleepy and just go to sleep, right? No, he then proceeds to scream for about an hour to hour and a half later. I know he is tired, but c'mon, what do I do? He does the screaming thing during the day too, especially right when he needs to go to sleep. I don't feel like I have help most of the time either. I really feel like I am holding a screaming baby all the friggin time! I am just at a loss, and feel so incompetent as a mom. Let's see if I can upload some pics of the little devil.