One of the causes of having back pain is longer sitting and not maintaining the proper ergonomics As far as complaints goes take proper rest and use hot water bag and some topical analgesics like volini

I think we need more details . Do not hesitate to see a Orthopedic consultant

Do x ray coccyx-AP/Lat. 

Avoid aggravating factors like sitting for long or long drives, start back and hip stretches. Hot fomentation of affected area. Muscle relaxation medicine. check vitamin deficiency. If it's non specific then will resolve soon

Hot water massage Sit on soft surface Powergesic gel Medicine.. 5-7 day it will subside

Looks like your backache is entering next stage in form of buttock pain radiating to leg. Needs clinical and radiological evaluation by Orthopaedic surgeon to rule out root cause.

Its seems you are describing Sciatica. You need to visit an orthopaedic surgeon. Get an xray done. May need to evaluate to rule out disc problem. If you are driving scooty since long or have a desk job requiring long sitting hours it may have caused the problem. Do not ignore. Meanwhile do hot packs for your back and avoid lifting heavy loads.

It might be coccydynia, don't sit on hard surface. It require pain management and physiotherapy

It may be sacroilitis, needs blood test to confirm the same

For an accurate diagnosis, a detailed assessment with clinical examination and proper history followed by appropriate investigations is needed.

Lower back pain radiating to legs. Seems to be radiculopathy.need detailed examination Followed by medication and physiotherapy

It's a nerve that is getting compressed in  your hip area.