I need some advice about what happend at my doctor visit the other day?

My 2 year old daughter has been sick throwing up and diahreah on and off for around 3 weeks. I tool her into the doctors office the other day and among other things they wanted to test her blood sugar for diabetes. They brought in the glucose monitor, pricked her big toe and tested her blood sugar. Anyway three days later she woke up with nasty looking white bumps and legions all over her toungh and mouth. They are very painfull and she could barely eat or sleep because of them. I took her into the dentist today, and come to find out he said that she has "oral " (gingivostomatitis) I was very shocked to hear this. The dentist said you get it from kissing, using dirty needles or from touching your eyes with dirty hand. Wel I started thinking after I left the dentist, and it came to me. I am wondering if they forgot to change the needle at the doc office when they checked her blood sugar! Kinda seems wierd that 3 days after being tested with a needle she contratcts .