Bodymedia problems!

I have been using a bodymedia armband for a little over a month now. I bought it used from ebay and havent had any issues with it until now. Yesterday I cleaned around my house for about 3 hours. Washing dishes, Vacuuming, etc. just light activity. also on that day I walked on the treadmill for 66 min. When I synced it that night it said I was only active for one hour and 6 min. The time that I was on the treadmill. It has always tracked my activity while cleaning and such and i'm wearing it the same as I always have nothing has changed! Today again I was on my feet for 5hours cleaning and when I synced it just now it said I had 2 min of activity! I don't know if it's just me or the armband is going bad or what but it is really driving me crazy!! Do I just need to toss it and get something new? I've tried wearing it tighter and it hurts too much to do that all day open to suggestions thanks!