I think everyone goes through some form of this when they finish a project, so you're not unusual by any means. Just give yourself a few days to level off from the last quilt until you start the next one and you should be fine. Or, as suggested, do a few small things just so you feel like you're still "working". I do this a lot, but I got a bonus last year when I had only a couple of days when that happened...the rest of the time I quilted and pieced like a house on fire! Good luck however you deal with it!