Hi Charlene,
mymary's reply is more helpful than what I had planned to share. I begin by saying I am sorry you have an unhappy baby on your hands. It is incredibly difficult to cope with, much less gush over, a baby who cries incessantly and does not sleep much.
Perhaps the solution to your baby's weight gain/crying/lack of sleep is biological. I like the direction mymary suggested. I can't think of any other intelligent suggestions to pursue at this time for the weight issue.
As far as the crying/sleeping problem, I have vast experience thanks to my now 5 year old. Truman was a high need baby from the moment he was born peacefully into the water. He *screamed* for hours a day. Never slept longer than 45 minutes in a row and that was with me holding him over my shoulder and walking outside.
We took him to the chiropractor, a naturopath, the MD--nothing was physically wrong with him.

I tried eliminating fuss-foods from my diet, we co-slept, I wore him in every carrier I could afford to try, we swaddled, shushed, drove in the car, ran water nearby, bought a white noise CD, tried gas drops, a reflux med, colic tabs, gripe water, a heating pad, baby massage, infant swings, vibrating chairs, an Amby bed...still Truman cried. All we could do was make sure he did not cry alone.
He was our second child and we practiced attachment parenting with our first so we felt well-prepared for a high need baby. Whatever.

It was incredibly difficult to cope with the crying and lack of sleep. Truman screamed for the first 4 months and then cried for another 7 months. It was torturous at times.
I had many, many moments of anger and sometimes wished we had never had another child. I sometimes felt he ruined our lives. My dh an I were adults with good coping skills but our poor 4 year old was just stuck with a screaming baby in his house, in his car, in his mom's lap, 24/7. My heart broke for him.
We made it through and learned much about parenting along the way. Once Truman got mobile, he was much happier. We think he really hated being a baby. Truman is now our sweet, empathetic giver. He is very tuned in to people's feelings. We love him so much. I truly can say it was worth the bitter to have the sweet.
I sure hope there is a simple biological cure for your baby's unhappiness. If not, and it looks like you have a high need baby, I hope you find good tips and lots of comfort in the Sears books on parenting high need children. It was so good to know we were not the only people in the world with a challenging baby.
Many, many hugs momma...