Oral Ulcers due to Decovy Side Effects: Decovy (tenofovir alafenamide) is an antiretroviral medication, and while less common, oral ulcers or sores can be a side effect of antiretroviral therapy. The recent onset of symptoms in a patient on this medication suggests a possible correlation.

Aphthous Ulcers: These are common, recurring ulcers in the mouth that can be triggered by stress, trauma, or certain foods. Their appearance and the patient's symptoms could align with aphthous ulcers, especially if the patient has a history of them.
Oral Candidiasis (Thrush): This fungal infection can cause white patches and redness in the mouth, including the tongue. It's more common in immunocompromised patients, which could be relevant depending on the patient's HIV status and the effectiveness of their antiretroviral therapy.
Allergic Reaction or Irritation: An allergic reaction to food, a new oral care product, or another irritant could cause sores and swelling on the tongue.

Kaposi's Sarcoma: Although rare, Kaposi's sarcoma can present with oral lesions, especially in immunocompromised patients, such as those with advanced HIV/AIDS. Early detection is crucial for effective management.
Oral Cancer: While less likely, any new or persistent oral lesions, especially in patients with risk factors like smoking or a history of HPV infection, warrant consideration of oral cancer. Early diagnosis significantly improves prognosis.
Angioedema: A severe, potentially life-threatening condition that can cause rapid swelling of the tongue and other parts of the body. It requires immediate medical attention.

Eosinophilic Ulcer: A rare condition characterized by an ulcer on the tongue, often associated with eosinophilia. It's an uncommon diagnosis but could be considered if other causes are ruled out.
Behçet's Disease: A form of vasculitis that can cause oral ulcers, among other symptoms. It's rare and would typically present with additional systemic symptoms, but it's a consideration in complex or atypical cases.