don't get panic it may b hematoma due to injury to blood vessels while giving anaesthesia it will go by itself in 24-48 hrs.and for your mouth opening problem do hot water fomentation and try to open your mouth slowly if not possible take help of your hands and pull your mouth slowly to open it practice this 3-4 times a day surely u get relief very soon.in addition you can take tab.arflur mr twice for 5 days

Hi
On the day of extraction try using an ice pack on the outside of your cheek. Apply for 15 to 20 minutes at a time for the first 24 hours. You can use moist heat—such as a cloth soaked in warm water for the following 2 or 3 days over the swelling/lump.
Relax after surgery. Physical activity may increase bleeding.continue and complete the antibiotics your oral physician has prescribed .
Eat soft foods. Gradually add solid foods to your diet as healing progresses.
Do not use a straw for the first few days. Sucking on a straw can loosen the blood clot and delay healing.
After the first day, gently rinse your mouth with warm salt water several times a day to reduce swelling and relieve pain. you can continue using warm water saline or betadine rinse for over a week .
Do not smoke for at least 24 hours after your surgery. The sucking motion can loosen the clot and delay healing. Also, smoking decreases the blood supply and can bring germs and contaminants to the surgery area.
Avoid rubbing the area with your tongue or touching it with your fingers.
Continue to brush your teeth and tongue carefully.
take care.