Mam,Looks like you have a cavity leading to food lodgement.You need to visit a dentist who will take care of the problem For the time being try using an interdental brush to remove the stuck food particles.
Dr Suman Makam
DO NOT USE TOOTHPICK !!!
As you have not mentioned. This could be a case of Food Impaction (Food Lodgement in between tooth Space) or Early stages of Pericoronitis due to Molar tooth Impaction or even a simple Cavity (Dental Caries)
1. If its Food Impaction (Food Lodgement), Consult a Dentist about proper brushing techniques, Enameloplasty (Smoothening out of Roughened enamel Cusps), Scaling or Root Planing in case of Sub gingival Plaque (Tartar buildup below the Gingival line).
2. If it is a Impacted molar causing Pericoronitis (A form of infection in between the Impacted tooth and Impacted Molar). You must consult a Dentist IMMEDIATELY for treatment. This could lead to serious Oral infections and Halitosis (Bad Breath). Which is both unpleasant for you and the People around you.
3. If it is a Dental Caries (Cavity), again please a consult a Dentist immediately as this could progress to total destruction of Tooth structure. Which if let to Progress will lead to Tooth extraction as a final resort, Thus complicating the treatment further and robbing you of a completely healthy Tooth which could have been saved with a simple Filling.
PLEASE DONT USE TOOTHPICK !!. Contrary to common beliefs, Toothpicks do more harm than Good. As you cant really see what is going on in your mouth until a Dentist has a look, So please always make sure to visit your family Dentist or the Local Dentist near you.
Note : As you have not specified any details of Pain, Swelling or Bad Breath. Please dont consider point 2. Its most probably a simple Dental Caries or Food Impaction. Not to worry, These conditions are treated with simple Dental treatments (If looked into at its Earliest) comprising of Mostly one Dental Sitting depending on your Oral Health.
Goodluck and Godbless :)