@mediocreoblongata you didn't say how far out from surgery you are and your profile is incomplete. It's pretty normal in the immediate post-op phase to have trouble getting your fluids in. You're healing. Take it slow, sip, do not gulp or try to get in large amounts at one sitting. Sip throughout the day. If you're more than 6 weeks post-op and it hurts to drink water, you may want to contact your doctor.
Regarding the NSAID debate: For both my Lap Band and my Sleeve, I was told no NSAIDS. That being said, the doctor also said that after 6 months out, an OCCASIONAL NSAID will not cause permanent damage. It's the routine taking of NSAIDS that cause cumulative problems. Also, they are more damaging when taken on an empty stomach.