20 weeks and 2 days post op of Tummy Tuck, the end of my incision changed, raised, and itchy. Is this normal?

Scars go through changes as part of the healing process. This is common. If it persists or worsens, see your plastic surgeon to make sure that you aren't spitting a stitch or require treatment for scar hypertrophy.

It is best to have the scar evaluated in person by a BoardCertified Plastic Surgeon, especially given that it has become raised, red, andsore, which could indicate a reaction to a suture. Itchiness is expected overthe course of healing and may be remedied by an over-the-counter ant-itch cream.Karen Singer, M.D., P.A.Harvard GraduateBoard Certified Plastic Surgeon

Scars are typically itchy as they are healing.  You seem to have a bit of redness on one side and not the other - perhaps a suture reaction.  You would need to be seen in person for an accurate diagnosis and treatment plan.