Infective Endocarditis: This is the most direct and likely diagnosis given the context of the question. It is characterized by infection of the heart valves, typically caused by bacterial pathogens, and can present with a variety of symptoms including fever, heart murmur, and embolic phenomena.

Non-bacterial Thrombotic Endocarditis (NBTE): Also known as marantic endocarditis, this condition involves the formation of sterile vegetations on heart valves, often associated with hypercoagulable states or malignancy.
Libman-Sacks Endocarditis: This is a form of non-bacterial endocarditis seen in patients with systemic lupus erythematosus (SLE), characterized by the formation of vegetations on either side of the valve leaflets.
Endocardial Fibroelastosis: A rare condition characterized by a thickening of the endocardium, which can mimic some aspects of endocarditis, particularly in terms of heart failure symptoms.

Acute Rheumatic Fever: Although less common in developed countries, acute rheumatic fever can present with cardiac manifestations that might be confused with endocarditis, including valve inflammation.
Prosthetic Valve Dysfunction: Patients with prosthetic heart valves are at risk for valve dysfunction, which can mimic endocarditis, including symptoms of heart failure or embolic events.
Cardiac Tumors: Primary or metastatic cardiac tumors can sometimes be confused with endocarditis, especially if they involve the valves or cause embolic phenomena.

Infective Endocarditis due to Fungal Pathogens: Fungal endocarditis is less common than bacterial but can occur, especially in immunocompromised patients or those with prosthetic valves.
Q Fever Endocarditis: Caused by Coxiella burnetii, this is a rare form of endocarditis that can be difficult to diagnose and often requires specific serologic testing.
Tuberculous Endocarditis: Extremely rare, this condition involves infection of the heart valves by Mycobacterium tuberculosis and is usually seen in the context of disseminated tuberculosis.