Here are some links:
http://www.drgreene.com/21_1051.html
http://www.askdrsears.com/html/5/t051300.asp
http://www.babycolicremedy.net/How_Long_Does_Colic_Last.html
http://www.med.umich.edu/1libr/pa/pa_colic_hhg.htm
I'm sure you have tried lot of things. Perhaps best to take her to the Doctor to rule out anything else... from hunger, to teething, to reflux, to gas, to illness, to digestive pains etc. It could be anything, since she is already 4 months old and still having this concern.
If it is colic, ask you Doctor for advisement, again.
Some babies are also just "sensory sensitive" and this throws them for a loop....be it for over-tiredness, to too much light or noise sensitivity, to tactile sensitivity, to allergies, etc.
My daughter had gas problems and was also sensitive to noise. She still is sensitive to noise, although has grown out of it a lot, and she is 5 years old. BUT, we'd have a hard time putting her to sleep or nap when she was a baby and toddler. So that is the way she was. For me, I was nursing her and would co-sleep with her for naps and bedtime... as this is the only way she would wind-down and then go to sleep. It was, after trying ALL different techniques, the only way to go with her. She was also very clingy, and fussy at times when she was tired. My son, on the other hand, thankfully, is much more easy going.
Keep up with consistent bed/nap time routines... it does help. Perhaps she needs more of a transition time before bed... to wind-down and then segue into bed. Also, make sure she is getting her naps... this is very important. Without naps, a baby gets too over-stimulated and much too tired, and over-tired babies and kids actually have a harder time to go to sleep.
For my sister when she was a baby... my Mom said she had colic... and in her case it was because she had a very sensitive system and was allergic to dairy... and in those days, babies were on formula, at least for my Mom's case. My sister even as an adult has a sensitive digestive system still, and to dairy... and food wreak havoc on her stomach and moods. So.... this is something to think about. Some are just more sensitive to what goes in their body.
Well I know it's not easy... but all the best,
Susan