Hello dear, Thank you for your contact to health care magic. I read and understand your concern. I am Dr Arun Tank answering your concern. Such severe ulcer with candida infection points towards some kind of immunosuppression. I advice you should test for the HIV and other immunocomprmise condition plus blood sugar examination. Prolonged antibiotic therapy with broad spectrum antibiotic therapy like Doxycycline can cause such a infection. You can take the treatment for the candida infection like fluconazole tablet 150 mg once a week for long period of three to four month. Please maintain optimum blood sugar. This will help the drug to do it s good action. Maintain good hygiene locally as well as general. This equally help prevent the infection. Please adopt good hand washing practice. This is help ful in the treatment equally as drug can do. Avoid sex until you are all clear from the infection. I will be happy to answer your further concern on bit.ly/DrArun. Thank you, Dr Arun Tank Infectious diseases specialist, HCM.