Can a baby that is 5 1/2 months old have colic?

My son was diagnosed with colic at 3 weeks old. He's now 5 1/2 months old and he still acts like he did when he was 3 weeks old. The crying doesn't stop and gets worse still as the day goes on and evenings. I was told colic usually disappears around 3-4 months old, so why is my baby still acting like he still has colic at 5 1/2 months old?