Hi.. Welcome to HEALTHCARE MAGIC.. I have gone through your query and can understand your concerns.. As per your complain Penicillin and Amoxicillin are antibiotics that are used to treat bacterial infection and belong to Penicillin group of antibiotics whereas Diflucan contains active ingredient Fluconazole that is an antifungal medication and is used to treat yeast/fungal infections.. Both these are totally different from each other and belong to completely different group of drugs and treat altogether different kinds of infections.. Although you can be allergic to both groups leading to allergy symptoms of rashes and itching.. You should stop taking these medications and take anti allergic like Levocetrizine or Benadryl for relieving the allergy symptoms.. You should then consult an Allergist and get evaluated and he can advise you allergic tests to check for the allergies and also find out which antibiotics and anti fungals are compatible with your body that you can take without any reaction so that you can take them if you even need in future.. As of not take anti allergics and apply a steroid based cream over the itchy areas for relief.. Calamine lotion can also be applied to soothe skin as well as cool compresses will help.. Hope this information helps.. Thanks and regards. Dr.Honey Nandwani Arora.