Sometimes i feel a pressure(a little strong) on the right lower quadrant of abdomen and weak pain. what it can be? (( i don't have appendix ))

RLQ pain: There is a long list of reasons for pain in the right lower quadrant. Since you are male and you don't have your appendix anymore, it decreases the list a bit. If you have severe pain with decreased appetite, vomiting, and/or fever, you might be having an emergency for which you should go to the emergency department. At a minimum you should see your doctor about this.