



What you most likely have is either a yeast / fungal infection (usually through vaginal) or a bacterial (usually through anal) infection. If you had vaginal get some clotrimazole or miconazole from a chemist or suchlike and make sure you follow the instructions carefully, if you had anal you are likely to need the correct antibiotic cream and/or tablet prescribed to you by a doctor.
However, as you have had the infection for a week+ you may need to get a combined fungal, bacterial and steroid ointment prescribed to you - to check on this either speak to a pharmacist, a doctor or go to a Walk-In Sexual Health Service …