Trying To Find What Is Going On With My Mother.

Question: Trying to find what is going on with my mother. A couple of months ago she got a small black line on her middle finger, over a 3 week span the line started spreading through out her nail. Let me make this clear, there was NO injury what so ever to the finger. A couple days later the pain set in. There was pain during the day when she was up moving around but nothing she couldn't handle but when she would lay down to go to bed the pain was so severe she would be in tears, said it kept feeling like someone was stabbing her finger repeatedly with a needle. The Dr. here did lab work, everything came back fine. Over the next couple of days it swelled up, she went back to the Dr. and she was able to XXXXXXX it and send it out to be tested. A week later the results came back that it was a bacteria called Endocarditis. She does not have any heart problems including an infection and she goes to the dentist every 3 months to have her teeth cleaned and examined and there is no infection there either. She has no symptoms of the endocarditis other then the lab work coming back that says it is. After the Dr lanced it there was a great deal of relief and was finally able to sleep after a week. They finally started her on antibiotics and it went away, she did end up losing her nail but is now starting to grow back

A week ago she showed me the middle finger on her other hand, there was a small black line, told me she was going to keep an eye on it. Yesterday I saw it again and it has started spreading throughout her nail and told me the pain woke her up in the middle of the night, again kept her awake most of the night last night. She went to her Dr. yesterday (the same one she saw before) and now she wants to treat her for a fungus and prescribed an antibiotic.

I feel like there may be an underlying condition that is causing this but all the research I have done comes up with nothing. Then the fact the lab came back as Endocarditis is really confusing me since they have checked her heart and done lab showing no infections.

Really hoping someone else may have an idea of what is going on so we can tell her Dr. and maybe get a referral. I should also note she does have arthritis and is currently taking celebrex for it