hello patient, spondylitis is wear and tear of spine and will not occur immediately after LSCS. your problem seems to be a general weakness of back muscles due to deficiency of
calcium, d3 and magnesium after delivery. this is very common after delivery and may take a year to correct since body's requirements are increased during feeding of baby. also your other problems namely ibs and migraine are many times related to stressful mindset which is again common in post partum period. try meditation and breathing ex instead of aggressive yoga poses initially.
Next Steps
do blood tests for
calcium and vit d3. consult a good physiotherapist for developing strength in back muscles. avoid painkillers which can aggravate your ibs. try to get in a happy midset and enjoy time with kid.