suhay1,
Femurs can take quite a while to unite. While it is variable, it usually takes around 10-20 weeks for the bone to heal, and that does not include the time for the soft tissues to be rehabilitated.
Limping is usually due to one of three things: pain, decreased range of motion, or decreased strength (or a combination). Until all of these are addressed, you will have a limp.
Since you are having episodes of intense pain, you should contact your surgeon. Theoretically, your pain should be getting better and better as time passes. For you to continue to have setbacks, with intense pain, something is going on, which needs to be checked out.
Hope that everything is okay, and that is just part of the post-op healing process. But, again, you should be getting better, not continuing to have problems.
Good luck.