usually 5 day oral antibiotic course is sufficient to reduce the swelling . the main problem in your case is not the antibiotic but the lock jaw due to spam in your muscle, so along with antibiotic take muscle relaxant
too. do warm saline gargles 5 to 6 times a day and try to break the muscle spam by putting ice cream sticks between your front teeth, gradually increasing the number to increase the mouth opening. .
once the lock jaw is open then rest of the problem can be taken care of subsequently.