Everything you've done sounds reasonable. If she's crying it is for a reason. She's trying to tell you something.
Is she gassy? If she is squinching up her face and pulling her legs up, she might be. There are ways to hold and move her that will help relieve her. I found diagrams in the Sears Baby Book that were a lifesaver. Dairy is a good place to start, but broccoli, cabbage, tomatoes, and citrus could also be problems.
Is she getting enough sleep? Babies that age start needing a regular sleep schedule (total 15 or more hours with naps). Before 3 mos they just sleep wherever, but it starts getting more difficult around 4-5 mos. Dr M Weissbluth has a book that may help (Healthy Sleep Habits, Happy Baby).
What about clothing textures? Some people are very sensitive to what touches their skin. (I need the seems on my socks lined up or they hurt my feet). Try all cotton clothing, paying attention to softness inside.
If you aren't already, try holding her as much as you can. Your touch and smell may sooth her. A baby bjorn might come in handy. A swing may also help.
If all this fails, sometimes babies just cry. All you can do is hold them and do the best you can. You may need to get a little extra help for yourself so that you don't burn out. Even an hour can be a life saver.