8 months old - day sleeps disappeared!

Hi Everyone,
My 8 month old has become a nightmare day sleeper. Since birth (well, after the horror of the first few weeks settled down ;)) he has been a fantastic day sleeper. He would go down wide awake and fall asleep by himself for 2-3 hours every time.
Around 6 weeks ago, this stopped suddenly. Now we fight over every day sleep. He screams the house down and simply refuses to sleep even though I know he's completely exhausted. His night sleeps have suffered a little (waking sometimes) but are still pretty good.
I've been telling myself that it's just a phase but it doesn't seem to be ending....
I just don't know what to do with him. The more I go into his room to try and calm him, the more worked up he gets. If he does finally drop off, he'll sleep for 20-30 minutes max. After he wakes up, there is absolutely no hope of getting him back down.
I'm tearing my hair out! Any suggestions?

for me, it comes down to what techniques you are using. It sounds like he used to be a self settler, but, perhaps it has changed somewhat for him. Aiden went abit sideways with his sleep at about the same age. Personally, I would drag a chair into his room, and rock him to sleep. Once you get him back into the routine of having a day sleep, then, start weaning him back of the rocking.

I can only comment on what we did, but DS wouldn't sleep either and I just found it easiest to put him on the spare bed and lie with him for a while until he drifted off or got really calm and sleepy. Then i'd put him in his cot.

I did eventually stop doing this though (or i would have had no life - and no-one else would be able to settle him!). Maybe after about 2 weeks.

He's pretty good now.

Thanks for you reply Debbie. I've been trying to rock him off to sleep but while he's in my arms he's all smiles, chatting away and just looking around at everything. I can rock for a very long time with not a hint of him starting to fade.
A lot of the time I end up thinking 'oh well, he musn't have been tired afterall', so we go back to the lounge room and he's back to being tired and grizzly!