((Hugs)) My 7yr old was a cryer. We thought there had to be something medically wrong with her. After numerous Dr visits and several different tests we were told she was physically fine. That's when I started trying just about everything I'd ever read or heard about. Some of them worked better than others.
First, I was breastfeeding and had tried to eliminate different foods in my diet but gave up on that. Instead at night I started co-sleeping, so she could nurse on demand and I could sleep. During the day I held her a lot, so much so that I had to wear wrist supports (she was heavy). If I couldn't hold her I would put her in the swing, which worked well with a sound machine. I bought a portable one from Radio Shack and the train or wind sounds worked best. This was great because I could take the machine with us for car rides and visits. (Before I bought the sound machine I was using a blow dryer on the cool setting.) Better than the swing was the vibrating chair, especially when I needed to take a shower or wanted to leave the house.
Things that didn't work were: car seat on top of the washing machine or dryer, gripe water, mylicon drops, slings, and swaddling. There was never a time where she would cry herself to sleep. The longest we let her go was 30 mins and I was ready to smother her. It goes without saying that was not an option, but I understand your frustration. My DD also hated to be held by anyone but me for a good 6 months. It was amazing when her older sister was able to rock her to sleep when she was 7-8 months old. She is now able to fall asleep anywhere, even on the floor! So they can/do change. Hang in and I hope you find something that works.
-Darri 39, DH 34, DD 19, DD 8.5, DD 7, and DS born 03/29/08