My dad had a back (spine)surgery two weeks ago. he started vomiting, he has constipation and his stomach is bloated all the time. what shoild he take?

Go see a doctor: Post surgical complications can occur. Your dad could have an ileus. Maybe he has a infection in his abdomen. Does he have a fever? I would call your surgeon and let him know about this.

Pain medication?: This could from pain medication he is taking. If this cannot be altered, consider using miralax (polyethylene glycol). If this does not resolve he should be evaluated by the surgeon.

This may be due to: Pain post op, less mobility post op, use of narcotic medication postop or even an ileus residual post op (bowels not fully functioning). If he had an approach thru the abdomen, this is more likely. However, a gastritis or an ulcer can also be triggered from stress of surgery & so can a gallbladder attack. He may also be dehydrating so see your surgeon. There are other possibilities-constipation.

Decrease the meds: Post operative meds for spine surgery generally include narcotics which frequently cause constipation/nausea/vomiting. Decreasing the narcotic meds and/or adding some non-narcotic pain meds can help. Also stool softeners.