Oh Kelly I am sending you the biggest because I know exactly what you are going through. I am going through this exact same thing with Olivia at the moment. We have now just entered our 3rd week of it and it looks like there is finally a light on the horizon (god I hope I don't jinx it by mentioning it). Olivia has been an absolutely nightmare. She refused to sleep AT ALL during the day and would scream for about 2 - 3 hours before she went to sleep at night. I couldn't put her down or be out of her eye line or the bellowing would start. I have spent 4 days at sleep school in the last two weeks. Please do not think tat you are alone in this. Luke is being very normal apparantely. I was told that this is a 6 month thing. They have finally learnt that crying/screaming brings us so they do it for that reason and not for hunger, wet or cold etc like they used to. The only thing we can do is perserve and hang in there. I know it is so hard and so much easier said than done. You get absolutely exhausted. Do whatever you need to to get through and hopefully it won't be long and your gorgeous little man will be back.
If you need anything at all feel free to PM, email or msn me. I'm here. I have cried so much in the last three weeks I can't believe it and boy have I taken it out on DH.
Good luck and if you find anything that works don't forget to pass on your tips.