Post-Covid Fibromyalgia: This condition is characterized by widespread musculoskeletal pain, fatigue, and tender points, which can include deep bone ache. The onset a couple of months into the long Covid healing journey aligns with the timeline for development of post-viral fibromyalgia, a known complication of Covid-19.

Vitamin D Deficiency: Prolonged illness and reduced mobility can lead to vitamin D deficiency, which is known to cause bone pain and muscle weakness. Given the context of long Covid, where patients may have limited sun exposure and altered dietary habits, this is a plausible cause.
Anemia: Anemia of chronic disease can occur in the context of long Covid, leading to symptoms such as fatigue and bone pain due to the lack of sufficient red blood cells to carry oxygen to tissues.
Hypothyroidism: Some patients may develop thyroid dysfunction post-Covid, and hypothyroidism can cause musculoskeletal pain, including deep bone ache, among other symptoms.

Multiple Myeloma: Although rare, multiple myeloma can present with bone pain and should be considered, especially if the pain is persistent and localized. It's crucial to rule out this diagnosis due to its severe implications and the need for early treatment.
Osteonecrosis: Covid-19 has been associated with an increased risk of osteonecrosis, particularly in patients who have been treated with corticosteroids. This condition can cause severe bone pain and requires prompt diagnosis and treatment to prevent further bone damage.
Bone Metastases: In patients with a history of cancer, bone metastases could be a cause of new-onset bone pain. Although less likely in the context of long Covid without a known cancer history, it's a critical diagnosis not to miss.

Osteomalacia: Rare in developed countries but can occur due to severe vitamin D deficiency, leading to softening of the bones and pain.
Paget's Disease of Bone: A chronic condition that can result in enlarged and misshapen bones due to abnormal bone destruction and regrowth, causing bone pain.
Sarcoidosis: An autoimmune disease that can affect multiple parts of the body, including the bones, causing pain and other symptoms. It's a rare consideration but should be kept in mind for patients with unexplained symptoms.