Hi Karen - we have a whole topic devoted to the starter! It is quite long but is full of TONS of information! Please check it out and if you cant find an answer to your questions there you can post over at that forum and you will probably get more response.
Likely there is nothing wrong. The starter goes through periods that are less active on occasion. You might want to try feeding it twice a day for a few days and see if that helps. It could just be using up all its food quickly and might be hungry.