Hello and welcome to HCM.
Thank you for your query.
From your description, it sounds like the forgotten tampon has resulted in the symptoms and even possibly a
urinary tract infection (UTI). I am assuming you have already taken the tampon out, which would not allow the infection to subside even with treatment, as the source, causing the infection was still present in your body.
So now that the tampon is out, I would advise you to visit a doctor to get diagnosed and treated instead of self-prescribing, but if you do not wish to do so or cannot, then you could continue with the
azithromycin which is used to treat UTI's.
A pinkish discharge is usually seen either during the first few days of a period or in the presence of an infection. In your case, the latter is most likely.
I hope I have succeeded in providing the information you were looking for. Please feel free to write back to me for any further clarifications at: http://doctor.healthcaremagic.com/doctors/dr-shoaib-khan/64581 . I would gladly help you.
Best wishes.