Doxycycline is not related to
amoxicillin and sulfa
drugs as it belongs to a different category of
drugs(tetracyclines).Side effects of doxycycline are headache, dizziness, blurred vision, body aches, flu symptoms,skin rashes,chest tightness,respiratory difficulty,nausea,vomiting etc.
I strongly advise you to ask your daughter to stop taking doxycycline so that no life threatening anaphylaxis occurs.