thanks for sharing your concern.
yes you are right , your left gum is inflammed and infected, this is called acute pericoronal abscess
now all the features that you have mentioned are SIGNS of infection. they are
, swelling , calor (heat), dolar (pain), fever, headache, lymph adenopathy , difficulty in swallowing, increased salivation, change in phonation , bad breath
and pus discharge from abscess having a sinus
for this i would recommend,
you must take an intra oral x ray to see the exact location of the third molar,size and amount of bone covering it .
your xray will help you to understand whether your tooth is fully or partially IMPACTED .
the abscess related to mandibular third molar, usually perforates the lingual cortex
and spread to the sub mandibular space .
abscess neglected for a long time discharge intra orally and some times extra orally too, it can also cause other space infections too.
now after consulting your dentist
,you can start with antibiotic and analgesic
. under its coverage you can go for minor surgical procedure for extraction of third molar .
meanwhile you can do warm saline rinses also use chlore hexidine 2% mouthwash, this will reduce the infection , take plenty of fluids and SEMISOLID DIET till you get over with your problem.