Swollen Tonsils and Glands

My daughter (10 Yrs Old) has had swollen red tonsils and swollen glands in her neck for about 3 weeks.  Her doctor stated she was positive she had mono but the all the tests show negative.  Due to the glands still be swollen at 3 weeks and no improvement with antibiotics doctor is still convinced she has mono.    Should I be seeking a second opinion?   Any reason to be concerned?

[alliesong]

Do you think it's possible she has something else..check for a mucus like substance on the tonsils. Is she sneezing and in pain? If so...it might be strep, tonsillitis or another viral infection. I thought i should suggest this since it seems that everyone and their cousin catches these types of ailments at this time of year. Anyways..if the tests came back negative and the doctor is still insisting and nothing is happening..id get another opinion.

hope this was helpful