I have a painful lower back near tailbone feels tender and inflamed, i gave birth six months ago, it's painful i even drag my left foot now which hurt?

Back pain: If you are dragging you left foot because of weakness thats very concerning. If you are dragging the foot because it exacerbates the pain thats a little different. You mentioned that it is inflamed which might suggest an infection. Either way you need a neurological checkup, some lab work (CBC, sed rate) and probably a CT of the lumbar spine and pelvis. See a doc soonest.

Physiotherapy: Vaginal birth can be associated with tail bone pain called Coccydynia. You can try some ice packs for a few days then switch to local Heat or Warm baths. Try local application of pain creams like Theragesic. Physiotherapy works well for the condition. Weight gain can also make pain worse. Watch your weight and have a goal in mind to lose 10% of your weight in the next few months. Good Luck!