For those not in the know, antacids control the acidity levels. Omeprazole signals to the stomach receptors to reduce/stop producing the acid in the first place. The difference is that, when your body senses a pH change upon taking the antacid, it provides some intermediate relief, but eventually the body senses the reduction and produces more acid to compensate for the shortfall, resulting in an even greater amount of acid. This can turn into a very vicious cycle very badly.
Ideally, you should be taking both Maalox with each meal and omeprazole on a regular basis every day, till your physician directs you to change course. 4 Maalox a day is actually a lot.