Hi Kaylalee !
I would definitely re-look into animation. Especially area like elbow, knee and ankle in all poses.
When elbow is back make sure there is enough space as it has volume of muscle, Fat. Any major penetration will pull the inner fat verts.
Also in the playblast arm is loosing volume especailly the tricep area. Do check the attachments of those muscles.
Ankle bone rotation will relax the sitting pose.
Are u doing Mus+Fat couple sim or simming each layer separately ?
If u r sim'ing muscle layer separately make sure there is no self penetration.
Also, do put on zSolver collision Detection, Currently in image its off