This is not medical advice.
In my career I’ve typically seen sciatica arise from two places. Either the piriformis muscle is pinching the nerve in the buttocks, or nerve roots are pinched in the lower back, causing pain to travel down through the buttocks, and sometimes all the way to the outer calf.
The Piriformis
If you have to have sciatica, this is the ideal cause, vs pinched nerve roots in the back. This really needs to be diagnosed by a doctor in person.
The piriformis is a small external hip rotator deep in the buttocks area, that lies over the sciatic nerve. The sciatic nerve is sandwiched between hip rotator muscles. When this muscle gets too tight, it pushes on the nerve, causing pain.
I typically see a history of too much sitting time, or recent travel, where people have increased sitting time.
Stretches
The typical treatment is to stretch this muscle in the manner shown above. Many pictures show the patient holding both legs up. Most of my patients are unable to do that, so I use a stool. I am pulling my knee towards the opposite shoulder. Sometimes I have to find the right position, where I feel the buttocks muscle stretching.
Weakness is also an issue. Bridging, and hip rotation exercises also help relieve this tension. The picture at the top of the article is a hip rotation exercise, as are the two above.
Heat and massage
In my experience, heat and massage also help decrease piriformis pain and tension. Massage can be difficult to maneuver on your own. I’m using a foam roller. Some people use a ball at home. Experiment with different sizes and hardness. Don’t be so aggressive with this that pain increases later.
Walking
In most cases I see, walking helps to decrease piriformis pain.
Sciatica from the lower back
This is a more serious issue, and is better treated with low back stabilization exercises described here.
Sometimes the industry likes to stretch the hamstrings to decrease low back pain. In my experience, this stretch can increase sciatica symptoms, as you are also stretching the already irritated nerve roots.
Progress
Some people have radiculopathy, which is pain and numbness running into the buttocks, and sometimes down the leg. If that pain starts to recede up the leg, this is a sign that the nerve pinching pressure is decreasing, and the patient is improving.
Each case is highly individual and unique. Hopefully you are able to see someone in person for guidance.