hi thank you for asking your concern and welcome to hcm. occasional constipation is not a big problem as it may happen with sudden change in food, sleep disturbance, change in place or sudden indigestion. in any of the condition it is self limiting. but as you said he feels full which may indicate to gastritis causing him fullness feeling. if he feels more after meals and burping is there then it is more likely a gastritis. i would suggest you tablet ranitidine one tab twise a day for 5 days atleast before the meals. syp cremaffin 20 ml during bed time can be tried for constipation, this syp can be taken during day time also whenever needed. some more things to do eat small and frequent meals, drink water only after one hour of meal single sip is ok after meals. walk for atleast 10 min after every meal. drink plenty water in between. i hope i answered your concern if you feel any doubt please ask us regards dr. abhijit