Generally there’s really not much pain after the biopsy. A day or so it can feel tender. I’ve had 13 over my cancer history and only one time the biopsy site was tender for more than a day. It felt more like a bruise. But nothing like you’re experiencing.
Bone marrow aspirate is exactly what happens. During a bone marrow biopsy, there is a larger aspirating needle that’s inserted into the bone along the iliac crest. It’s rich in marrow and is a good place to source a core sample and peripheral blood.

It may be totally unrelated to your biopsy. I’m not sure your daughter will see much. The point of entry is small. About the size of a ball point pen tip and should have healed by now/ But if there is any swelling inside it could potentially compress the sciatic nerve. That can also happen anytime if you slept in a weird position, bent over, picked up something heavy, etc. I have that issue myself occasionally and it’s age related. When that happens I see my massage therapist who is excellent at releasing the muscles and tension that causes my ‘pain in the butt and back’…

If this is sciatica there are a number of exercises which can help reduce the pain and strengthen the back to avoid it in the future. But check with your doctor first to rule out involvement from the biopsy. I really hope you get some relief soon!