pregnancy pains

I have pain in my lower back, lower belly (below my belly button), hips, rear pelvis region (by my butt), down to my knees and calves. it all feels deep and near the bone like there's weight pushing down HARD on my lower body, except for my belly and calves. it feels like growing pains in my calves. it's very painful to walk or stand, or sit in a hard chair (which I do for hours a day but can't work around it, it hurts more in the "butt bones" area that I mentioned earlier when sitting in a hard chair). I end up having to waddle/limp a bit, as well as walk slower. it hurts as soon as I get up after sitting for any period of time, and it only doesn't hurt if I'm sitting somewhere soft or with less of a completely flat surface.

doing research, I see it can be sciatica, PGP, SPD, or beb is lowering down. my SO says it's the last thing, that beb is getting ready to come out...but I don't know for sure. it feels early, I'm 28 weeks as of yesterday.

if anybody else is in this situation in weeks surrounding me (27 to 31-ish) how do you deal with this and what is it? I know I should see a doctor so they could tell me but in the meantime I want to know if you guys have an idea of it or deal with the same thing, because right now...