I have a slightly bulging disc, I've suffered with sciatica really really badly in the past. I did the damage lifting heavy stuff at work incorrectly doubled up with an ice hockey injury. At times I've had to jump out of my car in agony, I've had weeks off work, I had to sleep on the floor the bed was too painful and even stumble out of the cinema in pain. It kept coming back, I found things to avoid: don't sit on hard surfaces especially for long time periods. Don't stand up for longer than an hour, take a break, I found on nights out in town I'm hurting the next day. Cold weather brings it on too. I squat heavy and deadlift, but I can lift a 5kg plate with my back not correctly arched and throw it out for a week. It starts in my glute then it works down my leg to my calf and sometimes foot. I seem to have found a good balance and not had a flare up in a couple years but it used to be horrendous. You sound similar to me with the hard chair so it may be the same issue around the compression of the nerve. Good luck with it bro I know how bad it is. How old are you? I'm nearly 30, it started when I was 16 and was at its worst when I was 22.