My ankles hurt when i run?

I have recently started running, and have been going about 4-5 times a week, not for long runs, but doing a few laps of our local football field. The past couple of weeks, i have noticed my ankles really hurting when i run, and after i run, lasting a few days. Its quite painful, and is preventing me from running longer distances. Its not my trainers rubbing on my skin or anything like that, its like the muscle on the outside of each ankle, below the knuckle bit of my ankles (sorry dont know what its called) I have just got back just now, i couldn't run far, as they were extremely painful, and have noticed swelling on each foot, more so on my left ankle, feels like fluid stuff. Im not sure what is causing this, my boyfriend thinks tat it could be my trainers, they are just cheap running trainers, and i have low arched feet, which im told should be supported with better footwear when running? Could anyone please give me any clues as to what else this could be? Is it down to my cheap trainers and low arched feet? And what can i do to prevent this in future? Thanks