Apple payment card security code keeps disappearing

After trying many times to purchase in-apps from iTunes, like in games, I keep getting an error that my purchase can't be made at this time. I have an iPad Pro 12.1 that I use to play games on. Anyway, I couldn't get an answer from anyone, so I kept digging and discovered that when I checked my payment information the expiration date and security code of my card wasn't there. So I entered it. Went back and tried to purchase apps again. Couldn't. Reentered info many times and today the expiration date was there, but the security code was blank. I'm so fed up with this I could scream! There's a glitch in iTunes and apparently they aren't doing anything about it. Should I try to input my PayPal info for payment instead?