Need Help !!!!!

My 3 week old baby girl has been constipated for 10 days now. We’ve been to the doctors, they said switch her to soy, so we did, still no change, then they had us switch her back to what she was on. Went to the hospital and got her checked out, everything came back normal, she doesn’t have any blockages or issues making her not to poop. They wanted us to switch formula again, this time to Similac Alimentum, so we did and still no change. She pee’s a lot, witch is good, but she’s in constant pain and strains trying to poop. I don’t know what else to do. They suggested we help her with a q-tip and Vaseline, and we have, and it works, but she still doesn’t go on her own. Anyone else experience this with there baby.?