There is a difference between join pain and bone pain.
Join pain can have a lot of reasons in thals it's often due to hemochromatosis (to much iron).
When i had high ferritin levels i had join pain in both my knies it desapeared by reaching lower ferritin.
Most people with hereditary hemochromatosis describe this kind of problem and doctors missunderstood it as artritis.
Bone pain has other reasons.
Ineffective extramedullary erytropoiesis is very commun in unwell treated thal major and intermedia. It is a sign of continuous low Hb, the body try to counterbalance the deficience by producing more red cells in other tissues. There could be a lot of consequences due to this, for example neurological complications due to compression of the spinal cord, bone pain or epilepsy. The location and the expansion will determinate the symptomatology. A hypertransfusion regimen usually reduces these masses. It was also observed that Hydroxyurea act by increasing fetal haemoglobin levels in patients with thal intermedia. The most thal intermedia are folic acid deficient, maybe it would be good to take it.
Concerning this issue i found some articles, maybe they can help you.
Issargagrisil S., Piankijagum A., Wasi P. "Spinal cord compression in thalassemia. Report of 12 cases can recommendations for treatment." Archives of internal Medicine 1981; 141:1033-6
OlivieriNF "Reactivation of fetal hemoglobin in patients with beta-thalassemia" Seminars in Hematology 1996 Jan;33(1):24-42
Fucharoen S, et al "Hydroxyurea increases HbF levels and improves the effectivness of erytropoiesis in ß-thalassemia HbE disease
Fucharoen S, et al "Intracranial extramedullary haematopoiesis inducing epilepsy in a patient with ß-thalassemia/hemoglobin E" Archives of internal Medicine 1985; 145:739-42 Blood 1996;87:887-92
Concerning cramps. Thals are magnesium deficient. Since i was a little girl i had every night and sometimes at day cramps in my feet, legs, abdominal muscels, hands...., It desapered when i started to take regular magnesium. Try it you will take a lot of benefit of it.
God bless you