I take gas x every day . they told me that i may have gastritis... and if gas x is a drug , isn't it bad every day?

Not necessarily bad: Gasx is simethicone, which works on gas. Not necessarily bad. However, if you have gastritis, you probably need to deal with the acidity as well. Acid buffers or blockers would help the gastritis greatly. Buffers such as antacids like maalox, mylanta, tums, etc work well. Acid blockers like zantac (ranitidine) or Pepcid (histamine blockers) or prilosec/ Prevacid (proton pump inhibitors) are very effective.