I've been prescribed a month of antibiotics for possible lyme disease (elisa positive but western blot negative). if it's lyme how long would it be before they starts to work? if i feel no better after a month - does that mean lyme's unlikely? thanks?

As in the reply to your other question, Lyme probably is not the cause of these symptoms. No improvement on antibiotics tends to confirm it isn't Lyme. But this is a complex and somewhat controversial topic. See an infectious diseases specialist if not already doing so. In the meantime, be careful with online searching: the web is loaded with almost cult-like misinformation about Lyme. Good luck.