Feeling a hard lump right side of neck.

One week back I had a sore throat, it was painful while swallowing food. My parents also suffered from sore throat at the same time. Since then I noticed this painless hard lump in the right side of my neck. I had taken Azithromycin for 5 days and the throat pain went within two days of medicine...but the lump is still there. Is it due to the infection or something else? What is the treatment for this lump? Can this be anything serious? I am concerned as this lump is situated in the extreme right and down side of my neck with no pain but the throat pain was near tonsils. The pain(which is gone now) area and the lump area is different. I am sharing the picture pointing with the finger the location of the lump.