3 weeks post op Tummy Tuck, I am having a terrible itch and few red bumps below the incision and in my pubic. Is this normal?

A photo would be great to evaluate just where "below the incision" is.  Many patients have itching in or just outsied the incision after abdominoplsty during the healing phase.  Red bumps in normal skin areas are usually a rash while red bumps in the incision may be sutures that are dissolving but irritating ( may also be early signs of an infection but I doubt it by your description).  You should inform your plastic surgeon and have him/her re-evaluate your scar.Best of luck.Dr. T