Hello and welcome to HCM,
G-6-PD deficiency does not cause any symptoms normally.
It is only when the RBCs are damaged / hemolysed due to oxidative stress
Oxidative stress occurs secondary to consumption of certain groups od drugs- anti-malarials, sulpha group of drugs, fava beans, illness, infections, etc.
Back ache or sciatica is not associated with G-6-PD deficiency.
This disease causes blood related abnormalities like hemolysis, anemia, jaundice, ketoacidosis
, and acute renal failure
in very severe cases.
The drug that you are using is a morphine preparation.
As you have mentioned that the pain is increasing, it implies that you are developing tolerance for morphine.
This is only palliative treatment.
Treatment of the underlying cause can only treat the pain on long term basis.
The lower back ache can be due to arthritis, ankylosing arthritis, osteoarthritis
, nerve impingement, etc.
You need to consult an orthopediacian and / or rheumatologist
for clinical examination, investigations and thus management.
Thanks and take care
Dr Shailja P Wahal