Lyme Disease: This is often considered the most likely diagnosis due to its prevalence and the classic presentation of migrating arthritis (especially in the knees) and fever, following a tick bite in endemic areas.

Rheumatic Fever: A complication of untreated streptococcal infection, characterized by migrating polyarthritis, fever, and other symptoms like carditis and chorea.
Gonococcal Arthritis: Caused by Neisseria gonorrhoeae, it presents with migrating arthritis, fever, and often skin lesions, particularly in sexually active young adults.
Viral Arthritis: Various viruses (e.g., parvovirus B19, hepatitis B and C, and HIV) can cause arthritis that may mimic a migrating pattern, accompanied by fever and other systemic symptoms.

Septic Arthritis: Although it typically presents with a single joint involvement, in some cases, it can appear as migrating arthritis if multiple joints are sequentially infected. It's crucial to identify and treat promptly to prevent joint destruction.
Endocarditis: Infective endocarditis can cause fever and arthralgias/arthritis due to immune complex deposition or septic emboli. It's a life-threatening condition that requires early diagnosis and treatment.
Lymphoma: Certain types of lymphoma can present with systemic symptoms including fever and arthralgias/arthritis. Although rare, missing this diagnosis can have significant consequences.

Whipple's Disease: A rare, systemic bacterial infection (Tropheryma whipplei) that can cause migrating arthritis, fever, and gastrointestinal symptoms among others.
Relapsing Polychondritis: An autoimmune disorder that can lead to episodes of arthritis, fever, and cartilage inflammation, affecting various parts of the body.
Sarcoidosis: Although more commonly associated with pulmonary symptoms, sarcoidosis can occasionally present with arthritis and fever, among its wide range of possible manifestations.