Hi, brain or spinal tumours will have a different presentation (headache, vomiting, weakness of face/limbs, seizure, visual disturbances). Back pain, leg pain and arm pains in toddlers may be a manifestation of calcium or vitamin D deficiency. If the symptoms are bothering, we can get a serum calcium and vitamin D level done. A blood count with ESR will rule out associated anemia and chronic inflammation(although less likely here). Kindly discuss with your pediatrician Meanwhile, give him a healthy diet rich in fruits and green leafy vegetables. These will supply enough minerals and micro-nutrients needed for rapid growth in this age. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Muhammed Aslam T. K., Pediatrician