Well it's good that you are conscious and observant , it could be early stage of periodontal disease( pyorhea) which is known as gingivitis ( inflammation of gums) and can very easily be reversed by scaling and oral prophylaxis( cleaning of teeth ), visit your near by dentist to get it diagnosed properly and treated
Next Steps
please visit your nearby dentist
Health Tips
warm saline rinses , brushing twice and rinse after every meal,,,but none of these can replace your dentist ,, please visit asap