Suggest Treatment For Swelling Between Neck And Collarbone

Please can u help. I've noticed a swelling in my left side between the neck & the collarbone. It's not painful however I am aware of it. It's not there when I first wake up but develops more as the day goes on(from mid morning onwards). Other symptoms include pain in the joints (leg & occasionally arm) in left hand side. Other than this I'm fairly ok. Smoker, average drinker, minimal exercise. Can u offer any help.