J.,
I would definitely talk to the pediatrician. Your daughter might have reflux which is causing her pain when she lays down to sleep. My daughter had it as well and the medication helped tremendously. I hated giving any drugs to such a young baby but it's very safe and she desperately needed it. And after just a couple of months we were able to wean her off.
It's also a little bit of a misconception that a baby has to spit up a lot to have reflux. My daughter did spit up, but it never really made it into her mouth. This, apparently, is very common and is called silent reflux. A baby that sleeps better in an upright position might be a sign as well. Anyhow, do some homework and talk to the doctor. They might be able to help you out, even if it's not reflux. Doctors have heard it all before and usually have some great advice to share.
I will say that eight weeks is still a little young to be expecting any DECENT sleep patterns from your child but I can certainly understand how desperate you must be feeling and your situation does sound extreme. My son would only sleep in a vibrating bouncy chair so you might consider trying that. Most of them stop the vibrations after 10 or 15 minutes, but the one I had ran indefinitely and we loved it. Of course, it was pretty much shot a few months later from the constant use but it was money well-spent.
I would also highly recommend getting some kind of white-noise machine. This is the one I've had and it's served me well for several years (running all night long) and is still going strong:
http://www.sleepwellbaby.com/ProductDetails.asp?ProductCo...
White noise is calming for babies and will help them sleep for longer stretches. If you don't want to buy a machine, take the antennae off of an old boombox and find some clear static. Or turn the brightness down on your tv and switch it to a fuzzy station. A box fan is fine too but obviously not practical in the winter months. Even the fan in your master bathroom can be helpful if you leave the door open. Whatever works.
Also, swaddling was CRUCIAL to my daughter sleeping well at night. I know you've already tried this but maybe you didn't have the right blanket? We bought those stretchy thermal recieving blankets that (because of the elasticity) stayed wrapped around her pretty well. But she still wiggled out and the second she did, the party was over. When I get pregnant again, I fully intend to buy this little beauty to solve that problem:
http://www.miracleblanket.com/
And that's all the advice I can think of spewing at you for now. Just remember that this stuff always passes. As you're discovering, each kid is different and what was easy with one will be difficult with the other and vice versa. You're daughter is a completely new little personality but I PROMISE that you'll have her all figured out in no time.
My best advice is to find what works and stick with it....even if it means putting your daughter to sleep in a vibrating chair until she's six months old (guilty!). Or putting her down with a bottle when she's old enough to hold it (double guilty). Or throwing enough binkies in her crib to sink a small ship (EXTREMELY guilty!). We've all done what was necessary to get our kids to sleep so don't be ashamed of what you resort to.
And when all else fails, PRAY!
In the meantime, hang in there, Sweetie. Just remember that you're a great mom and you WILL figure this out. :-)
-S.