Tonic Water vs Gatorade

Nate has had Gastric Bypass so he cannot drink anything with sugar in it.
I read up on what Tonic Water has in it that can help with muscle cramps. It’s Quinine. Makes sense.
I’m going to get some Tonic Water today at the grocery store since I could not find it at Wal.
I did find Cranberry Juice with no sugar there though.
Nate and I both agreed that he should drink some every day to help at least try to acidify his urine to avoid another UTI, and that he will try to go more often.
I will also be talking to our doc about it tomorrow.
I would hate for him to have anything else happen.