What Causes Swelling And Pain In Feet And Ankles?

Two days back, suddenly my leg front side joint (connects the feet with leg) started paining, I was feeling pain while walking. Then I took brufen 400 tablet at night, the pain got reduced next day. That day I was busy whole day, walking and shopping. Today my feet is swollen and I feel pain while moving my feet.What could be the reason ? what medicines shall I take ? I had 1/4 of lemon at dinner for two days.I didn't hit my leg anywhere.

I'm women of 8 yrs old from India, age: 40