Hello, this is Dr. E. Greetings from New York! I'm so glad you posted your question for me to answer, and I aim to provide you with accurate info.
It is not uncommon for scar tissue to occur especially if there is a foreign body like grease in the wound. Many pieces of dirt and grease won't show up on X-ray. I would keep it elevated, and wrapped, and use ibuprofen for pain. If it starts to swell you may need a hand surgeon to open up the finger surgically and explore it and possibly wash it out.