Is it better to get a total nail alvusion if you having pain underneath the nail and not on the side?

Not straightforward: Removing nails is useful when there's an infected area underneath it being worsened by the nail digging into adjacent skin. In my experience, it's best to remove less if possible. I think the most important thing in your case would be to figure out what the cause of the pain is. If it's not infection, could it be something else? If so, i'm not sure avulsion is the right answer.