Mild swelling in left testicle. Tia!

Hi, lately I have noticed a slight swelling in my left testicle with an extremely  mild pain but uncomfortable in my daily life, it doesn't bother me when I lie down on bed, but while I stand or walk I sense a little uncomfortable. I consulted a physician a couple of months back but he gave me pain killer and asked me to continue for 2-3 days but I apparently dint happen to take more than once. I'm a civil engineer by profession so my work requires me to walk alot, about 1-2 km a day...my heels pain a lot whn I sleep at night I also wanted to know if this pain is related to the same problem or no... I googled and noticed that I have a mild swelling on the epididymis... I could be wrong.. Bt im extremely worried as I saw that this could even be something deadly or cancer. Kindly revert back to me on this ASAP...TIA