why is my apple pencil not writing smoothly?

I bought the new 2018 iPad with the apple pencil 7 months ago for school. Two weeks ago, my apple pencil stopped working properly. It does write, but it doesn’t respond to pressure like it used to. The lines look really bad and you can barely understand what I write. I thought it was the tip because I do use it everyday, so I bought new ones and replaced them but it didn’t change anything. The problem is not my iPad because I tried using other Apple Pencils with my iPad and they worked perfectly.