Musculoskeletal Strain or Degenerative Disc Disease: Given the patient's age and symptoms of lower back pain and fatigue, musculoskeletal strain or degenerative disc disease is a common and likely diagnosis. The chest pressure could be referred pain from the back or musculoskeletal in nature as well.

Iron Deficiency Anemia Exacerbation: The patient's history of iron deficiency anemia could contribute to fatigue, and if the anemia is not well-managed, it could exacerbate, leading to increased fatigue and potentially shortness of breath or chest discomfort.
Gastroesophageal Reflux Disease (GERD): GERD can cause chest pressure and discomfort, which might be exacerbated by lying down or certain foods. It's a common condition that could also explain some of the patient's symptoms.
Hypothyroidism: Although not directly linked to lower back pain, hypothyroidism can cause fatigue, muscle aches, and potentially some chest discomfort due to decreased cardiac output. It's a condition that needs to be considered, especially in a female patient of this age group.

Myocardial Infarction (MI) or Acute Coronary Syndrome (ACS): Although less common in females, especially at this age without other risk factors, MI or ACS must be considered due to the potential for atypical presentations, including back pain and fatigue. Missing this diagnosis could be fatal.
Pulmonary Embolism (PE): PE can present with sudden onset of chest pain and shortness of breath but can also have atypical presentations, including back pain if the embolism affects the lung periphery. Given the potential for fatal outcomes, it's crucial not to miss this diagnosis.
Aortic Dissection: This is a life-threatening condition that can present with severe back pain and chest pressure. Although rare, it's critical to consider, especially if there's a history of hypertension or other risk factors.

Spinal Tumors or Metastases: Although rare, spinal tumors or metastases could explain the back pain and potentially some of the systemic symptoms like fatigue. Given the patient's age and gender, breast or lung cancer with spinal metastases could be considered.
Osteoporotic Compression Fracture: While more common in older individuals, osteoporotic compression fractures could occur in this age group, especially with a history of iron deficiency anemia, which might indicate poor bone health. This would primarily explain the back pain.