Okay, never used Cell-Tech so I didn't know that was suggested. I still think its alot of water so you could try not taking that second glass and see if it helps.
Also not all creatines are created the same, if you finish the Cell-Tech and still have stomach problems or didn't like the results, you can always switch brands or even types of creatine. Alot of people have indegistion problems with different brands of creatine. A good place to start is to check out reviews of different brands at places like BulkNutrition
which also has good prices.