My son tripped on the side of his left foot today at gym its painful he can't stand on it and we treated it with ice and ibuerphone

You : You are exactly right as far as the ice and Ibuprofen are concerned. In addition wrap his foot (not too tightly) in an ace bandage. In addition he should keep it elevated and rest it for at least a week. If his pain worsens and he is having difficulty ambulating (walking) and/or his foot becomes very swollen, red, or extremely tender to touch, then a medical evaluation is in order.

To : To be on the safe side, my recommendation would be to visit a foot and ankle specialist who can take an x-ray of your son's left foot to see if there is any fracture and or dislocation. Most likely, however, your soon probably sprained his foot and or ankle and that is the reason why it is swollen and painful. He should rest his foot and keep it elevated. You can put some ice over the swollen area until the swelling subsides (but don't put the ice directly on the skin). If it is just a contusion or a sprain, then it will definitely get better in about couple of weeks. If however, there is a tiny fracture, then, your son will need to be in a boot for at least 4-6 weeks until the fracture heals.