Inconsolable cries every night

My baby is 3 months and since 3 weeks ago, every night from 11pm to 2.30am, he would cry and scream suddenly with his leg stretched and stiffen out. Thought he was hungry but he doesn't want to drink. Sometimes carrying him works but I'm not sure if it's colic? I gave him gripe water in his feed and he's pooping well. I don't mind the exhaustion but my heart pained to see him going through this nightly. Anyone has advise? #advicepls