HI Sitting on a seat can compress nerves uin legs which results in numbness or tingling often refered to as paraesthesia by patient. However as you are having digestive problems its possible that your vitamin B12 levels are quiet low leading to demylenisation of nerves also.Vitamin B12 plays an extremely important role in both the synthesis and the maintenance of myelin, so B12 deficiency can cause the protective myelin sheath to deteriorate over time causing tingling and numbness referred to as peripheral neuropathy.Without myelin our nerves will no longer function properly, so basically vitamin B12 deficiency causes peripheral neuropathy. It will take 3 months for the things to be better as it is a gradual process Advice Vitamin B12 levels Vitamin B12 substitute for 3 months if found low.