Hello there...
Sciatica pain starts from lumbar spine and travels downwards crossing your hips, knee & calf. It's a stabbing pain. Since you haven't mentioned it, I think it's a localised backpain.
There are 2 types of back pain
1) Spinal origin & 2) S-I joint origin.
Spinal origin pain usually hurts in one posture that is either bending, straightening etc.
SI joint dysfunctional pain can create pain in any posture , even while resting ( when aggravated ). This pain can give rise to spinal pain as well. As SI joints on the hips are the foundation for the entire spine. If the foundation is shaky the whole spine will be 'unstable' or inefficient
Next Steps
I suggest you to try hotpacks for a 5 days ,4 times a day 10 mins just to relax and soothen the sore muscles and start with bridging , knee to chest bending alternate exercise, butterfly exercise ( slow )
if the pain doesn't go down go see a Physio
Health Tips
Google images for good Ergonomic posture for neck & back at home and follow it as much as possible.
It is too difficult to explain everything here . it's better to meet a physio in person and follow Physio advice as per the assessment done by the physio.