Hi,
Congratulations on your wonderful family!
I feel for you! I have an almost-four-month-old girl (my fourth child) who set the family record for colic and crying. For almost 2 months, she would cry (scream really) much of the day, on most days. She'd sleep great at night (5-7 hours!) but was inconsolable during the day. The swing was the only way she'd nap during the day (sometimes).
We tried everything, all the colic remedies. Some things that worked for our baby: Gripe water and Cocyntal Colic drops (natural remedies at the healthfood store), gentle massage, white noise (like a blow dryer or air filter).
I tried going off dairy for two weeks, but that didn't help. We tried a formula supplement once a day in case she wasn't getting enough breastmilk; that didn't seem to make a difference.
Finally, we switched her supplemental bottle to goat's milk, which is supposed to be closest to mother's milk, but we add a little almond oil, brewer's yeast and molasses; I've read people also just use plain goat's milk. It's supposed to be the easiest to digest, and wow, it did seem to make a difference! Now she's like another child altogether; smiling, napping, and growing!
We get fresh goat's milk from an organic farm, but you should also be able to get it at the grocery store (Meyenberg brand).
Hope this helps! More than likely, this will pass; colic rarely lasts more than 3 to 5 months. Hang in there!
Blessings!