Hello and Welcome to ‘Ask A Doctor’ service.
I have reviewed your query and here is my advice.
It looks like your new medication are the culprits for
oral thrush and mouth ulcers as both steroids (
Prednisone) and antibiotics (Doxycycline) can cause mouth ulcers and
fungal infection that is white buildup that you are experiencing as a side effect.
As antibiotics damage the good bacteria of the mouth that are responsible for resisting any infections and also steroids that reduce the resistance of the body therefore both can cause reduced resistance to infections and the opportunistic organisms like yeast overgrow causing infections like thrush.
So, my advise to you is to consult your physician and get examined so that he can reduce the doses of medications if possible to relieve the symptoms. For now you can start gargling with antifungal mouthwash like
Nystatin mouthwash and suck
Clotrimazole lozenges.
If the sores are painful and there is soreness in mouth then you can gargle with numbing mouthwash containing Lignocaine. Take vitamin B complex supplements.
Hope I have answered your query. Let me know if I can assist you further.
Regards,
Dr. Honey Arora