Had apicoectomy w/ cyst removal 5wk ago. Tooth/gum still don't feel right. Os says no sign of infection but didn't re-xay. Should I get a 2nd opinion?

Be patient. If no infection found, no x-rays are needed. Even though an apicoectomy is considered minor surgery, many people say that recovering from it takes 4-8 weeks. Take care.
First step. "doesn't feel right" is not much to go on. First step, return to surgeon for review. If you are still not comfortable, seek 2nd opinion, possibly with endodontist.
Oral surgery. Go back to your dr who did surgery and ask him what you feel and he can work on it.
It depends. How big was the cyst, in what area /tooth? If it was an extensive infection with a large area it may take a month or more to feel better. If the area is pink with no swelling and pain you are probably ok.
Healing time. Another x-ray may help, but it may not have been enough time to heal yet. Root canalled teeth never the same as vital teeth.
Healing. What you feel may or may not indicate a problem. Often, more time is needed for complete healing. If you trust your surgeon, rely on his\her judgment. However, there is nothing wrong with going for a second opinion. The x-ray was probably not taken as it would be unlikely to be helpful 5 weeks post-op.