My ds was like that, have posted loads and loads on here about him. He was dreadful in the day, never stopped crying, rarely smiled, wouldn't sit still without screaming. I just had to hold him and keep him moving all the time, I swear I didn't sit down for 9 months unless he was asleep! It was awful, very tense for us and obviously not a good time for him either.
Once you have checked and ruled out medical reasons for her crying then I think it's just a case of going with the flow. I know it's not much help right now but some babies are just like this for some reason. My ds always needed loads of physical contact with me, constant comforting, feeding, movement. Wouldn't go in car seat or pushchair without crying constantly.
I just figured that he was going to cry whatever I did so it was my job to just minimise the crying as much as possible, ie. feed him/ rock him to sleep (believe me people will tell you not to do it bad habbis and all that but it's about survival and doing whatever works). I gave up on puschair and just didn't go out much unless I had him in the sling, even then he'd scream if he got bored or tired.
If it's nothing medical then I think she will just out grow it. Some babies are just not happy and get really easily frustrated and scared by things. They need constant reassurance or stimulation. It's exhausting but you will survive. After my ds got walking it got better and better. Once he could talk he just was so much happier and just didn't need to cry as much cos he could say he wanted a drink, was bored, tired etc.
He's 2 now and is still sensitive, as in he needs warning if new people are coming to see him etc but he certainly isn't a screamer, rarely whinges and is lovely 99% of the time! Sorry this is long, just wanted you to know it will get better.