Hi... Can understand your concern... First of all you should have not got all the 4 wisdom tooth removed in one sitting..You should get one removed at one time or two (one upper and one lower ) of the same side in one sitting.. Now as per your question.. You have pain in lower left side as it was the only impacted tooth, there must have been more trauma to that region while removing that tooth so it takes more time to heal and so more time for pain and swelling to subside... If you have a hard ball over your cheek it may be due to underlying infection and inflammation as well as mouth opening gets reduced due to same reasons.. I would suggest you to take the full course of medicines which must be prescribed to you by your dentist and do mouth opening exercises like - Trying to open your mouth as much as you can under limits of pain toleration.. -Other is try to take your tongue out of mouth completely... These exercises will have an additive effect in improving your mouth opening along with medicines.. If the condition still doesnt improve visit your dentist for follow up .. One thing you should NOT DO is that you should not do hot fomentations ( applying hot water bottle) over that area.. Cold fomentations using ice can be helpful.. Hope you get well soon... Thanks and regards.. Dr. Honey Nandwani Arora..