Much more information is needed to address this. These questions come to mind:
Which finger is experiencing pain?
Is it your index finger (trigger finger?)
Or is it your pinkie attempting to get comfy at the bottom of the grip?
How many shots causes the pain? One, ten or many more?
What sort of grip are you using when this occurs? Are you using a two-handed grip or one hand grip?
Are you moving or stationary when this problem occurs?
If you are engaging in Dry Fire Practice, do you experience the same pain?
Clearly more information is needed to address your situation.
I can't imagine your trigger finger experiencing pain from the Shield trigger. The Pinkie problem is mostly related to the 7 cartridge mags. There is a neat and inexpensive add-on you can buy from Midway which extends the 7 cartridge mag and makes parking the pinkie easy and comfortable.
Proper grip usually doesn't cause any discomfort unless you are using a "crush grip" and squeezing entirely too hard on one finger. That should be easy to resolve. Take time to analyze your grip and adjust it to make the grip effective and comfortable.
Provide some additional input and better answers should follow.
HeadRAT in Florida