Rheumatoid Arthritis (RA): This autoimmune disorder can cause joint pain and, less commonly, symptoms like a croaky voice due to cricoarytenoid arthritis, which affects the joints of the larynx. The age and potential for systemic symptoms make RA a plausible initial consideration.

Laryngitis: Inflammation of the larynx can cause a croaky voice. If accompanied by joint pain, it might suggest a post-viral or infectious etiology affecting both the joints and the larynx.
Reactive Arthritis: Previously known as Reiter's syndrome, this form of arthritis occurs as a reaction to an infection elsewhere in the body, often in the gastrointestinal tract or the urethra. It can cause joint pain and, in some cases, symptoms like conjunctivitis and urethritis, which might indirectly relate to a croaky voice if there's significant systemic inflammation.
Ankylosing Spondylitis: A type of arthritis that primarily affects the spine, although other joints can be involved. It's less likely to directly cause a croaky voice but could be considered if there are significant systemic symptoms or if the patient has a history suggestive of spondyloarthritis.

Laryngeal Cancer: Although rare in a 29-year-old, any persistent or unexplained change in voice should prompt an evaluation for laryngeal cancer, especially if there's a history of smoking or significant alcohol use.
Acute Rheumatic Fever: This complication of untreated streptococcal infection can cause joint pain (arthritis) and, in rare cases, carditis that might indirectly affect the voice through respiratory or cardiac complications.
Sarcoidosis: An autoimmune disease that can affect multiple parts of the body, including the lungs, skin, and eyes. It can cause joint pain and, if it affects the larynx or lungs, could potentially lead to voice changes.

Relapsing Polychondritis: A rare autoimmune disorder that causes recurring episodes of cartilage inflammation, which can affect the ears, nose, trachea, and joints. It could potentially cause a croaky voice if the laryngeal cartilages are involved.
Gout: Typically affects older individuals but can occur in younger people, especially with certain dietary habits or kidney issues. It's less likely to cause a croaky voice directly but could be considered if there are acute, severe joint pains (especially in the big toe) and other systemic symptoms.
Sjögren's Syndrome: An autoimmune disorder that primarily affects the glands that produce tears and saliva but can also cause joint pain and, in rare cases, affect the larynx, leading to voice changes.