I believe the product that Heather is talking about is something like this:
http://www.toysrus.com/product/index.jsp?productId=226701...
I am not sure where you live, but if you do not want to go out and buy one, I have one you are more than welcome to. I am really big on giving away my baby stuff (even though I will probably have more kids) because I know how expensive kids are, and the less money the parents spend on clothes, etc the more money they have to spend on the babies well-being. It's not brand new, but it can be washed (we had to do this multiple times because our sons spit up a lot because of being preemies). It's similar to the one on the link above, but it doesn't incline like this one. We used them for our twin sons until they were about 2 months, then we started swaddeling them in receiving blankets. The doctor suggested this and it worked great. They have been sleeping through the night since! I also agree with the one mom who said that you have to let them "cry it out" sometimes. That's what we did when we broke the boys of swaddeling. It was so terrible, I've never heard them cry that hard and for that long, but honestly it wasn't so bad and it lasted 1 night. Cameron cried for about half an hour and Christian was so tired that he cried for about 15 mins and passed out (Cameron's screams didn't even wake him!). I suggest giving him some time in his car seat (he could be getting indigestion/acid reflux after eating and it might make it more comfortable for him to be sitting up a little), but once he starts moving more, take him out because it is unsafe. I hope my suggestions helped some and if you are interested in that sleep wedge thing, just send me a message, I live in Etters.