Gripe water or gas drops?

Has anyone tried these? My baby was born 5/13. At first he was doing really well with eating every 3-4 hours and sleeping in between. Now he is more and more fussy between feedings, very gassy, and just seems uncomfortable a lot of the time. He's also constantly waking me up in the middle of the night by whining and flailing his arms (this doesn't always wake him up, but I'm waking up every 10 minutes or so when this is happening). He takes Zantac 3 times a day for reflux and uses Similac Sensitive (I supplement with breast milk through pumping as able because he never could latch to nurse).