My quads, hamstrings, and knees are terribly tight post. Can I start trying to stretch them out?

It is three weeks after my I had Lipo on my inner thighs, outer thighs, knees, and banana roll. The PS said he also "lightly feathered" the cannula across my quadriceps. I am finally starting to feel like a human again and not just a giant, painful bruise. : ) My problem is that I have lost so much flexibility in my legs. I can't even bend my legs enough to sit cross-legged. My quads, hamstrings, and knees are TERRIBLY TIGHT. Can I start trying to stretch them out? Is this normal?