Originally posted by trekchic
I took it to the LBS and they changed the tube for me, and ever since, I can't keep the back tire inflated.
Trekchic-
It sounds like whatever caused your puncture in the first place might still be stuck in the tire. Pull the tube out and run your fingers around the inside of the tire. If you were riding in the grass chances are you'll find a small piece of sticker or thorn. You'll need to patch or replace the tube and make sure that you get every little bit of the culprit out of the tire, or you'll just keep getting slow leaks.