What is Dysthymia? Medication for it?

[randomperson]

I went to my Psychologist today and she mentioned dysthymia as something that I might have. I'm apparently usually very happy whenever I see I go there (my friends also say this about me), but about two weeks ago I went in and she said I looked melancholy. I told her I do feel this way often. I missed our session the week after that and then this week when I went back, she said she suspects I might have Dysthymia. She described it and it sounds like me, but I don't feel like this ALL the time, just maybe once out of the week and the rest of the time I'm pretty happy, or really happy as my friends put it. My Psychologist talked to me about taking medication and I don't know if I should since I'm not really sure what this is or if I want to take it. What is Dysthymia and what are some downsides of medication for it? Thanks.