I know all about this A.. My second daughter was a hold-me-all-day-or-I-will-scream-my-head-off kind of baby. What made it worse was - she didn't sleep through the night until she was like seven months old. Come to find out, everything I was eating (she was breast-fed) was making her tummy hurt. When we finaly gave up trying to figure out what foods I could and could not eat, and switched her to soy formula, it turned out she was allergic to it! The we switched her to Alimentum and she was much happier and more willing to do other things besides being held.
I remember one day calling my mother, who lived an hour away and telling her that I was just about to go off the deep end because of the constant crying and need of being held. She came down and gave me about a four-hour break to just go out and about and get away. That gave me enough of a recharge that I was able to handle the stress when I returned.
Maybe someone could give you a little break - even if it's only for four hours, some times that's all it takes.
Another thing - we used to sit out on our front porch on the porch swing for hours and watch cars go by, people walk by, etc. and that would calm her down. I could bring a book to keep my mind alive, and we would just swing and swing.
My oldest daughter was seven at the time and I felt so bad for her because she was stressed out by the either constant crying or me only paying attention to the baby. I had to make an effort to have my husband stay with the baby on his day off from time to time so I could have alone time with just her.
One other point that I hope can offer you some comfort is that looking back now...I remember the stressed out feeling I had during the early moments (and they are just moments in the grand scheme of things) of her life, but it was over pretty fast. Now she's still a higher-maintenence kid (drama queen to be more specific) than my first child (who was not a crier as a baby - I don't know if that's related or not), but life just keeps getting easier. And it most likely will keep getting easier for you.
There is nothing wrong with holding your baby either, by the way. And, there's nothing wrong with setting the baby down in a safe place and walking away for a while. A baby won't get hurt from crying! If you need a break, mental or physical, this is what I would do!
There are some great front-carriers too. That will take the pressure off of and free up your arms, and most carriers now offer good support for your back too.
My daycare provider just had a baby six weeks ago, and she carries him everywhere in this great little carrier.
REMEMBER THIS TOO: Carrying a baby around with you is the best form of weight training you can do. It's constant and the baby just keeps getting bigger. Your arms and back will be so strong by the time that baby grows up!
Time goes fast. This too shall pass.
God bless.
-J.