Vitamin B12 deficiency.

Vitamin B12 deficiency can manifest in various ways, and some of the symptoms can be quite unique or less commonly discussed. Here are some symptoms:

1. Glossitis and Mouth Ulcers: An inflamed, swollen tongue and mouth ulcers are sometimes early signs.

2. Paresthesia: A sensation of pins and needles, usually in the hands and feet.

3. Difficulty Walking: Nerve damage can lead to issues with balance and coordination.

4. Vision Disturbances: Damage to the optic nerve may cause vision problems.

5. Mood Changes: Depression, irritability, and cognitive changes like memory loss.

6. Glossitis and Angular Cheilitis: Inflammation of the tongue and cracking at the corners of the mouth.

7. Jaundice: A yellowish tinge to the skin and eyes due to high levels of bilirubin.

8. Shortness of Breath and Dizziness: Reduced red blood cell production can lead to anemia, causing these symptoms.

9. Heart Palpitations: Anemia from B12 deficiency can lead to irregular heartbeats.

These symptoms can vary in severity and may develop gradually. If you suspect a B12 deficiency, it's important to consult a healthcare professional for proper diagnosis and treatment.