HELP!! Formula Switch

My sweet little guy has had colic since week 3. He was on Nutragimen until week 9 but started having bloody stools. A pediatric gastrointestinal Dr. had us switch to Alimentum. She warned us about his poops being slimmy green and smelly but nothing was mentioned about his colic. It has gotten so much worse in the last 2 days. He has been on it for 4 days now and he has bouts of bad gas at night and doesn't sleep anymore. Is this something I need to wait out or is the formula not working for him? Please any advice would be helpful.