Actually, petrolatum is one of the gentlest ingredients on the face, and as far as dimethicone goes, it's YMMV for some people. Some people swear any 'cones clog their skin, others are fine with them.
Again hang in there - you're almost done unless that doc decides you need to do this again. At least this awful period is temporary and your skin will heal - hope this helps. Sounds like you're doing the right thing with a soothing cream too - I'm sure it must feel like a relief under such circumstances from the treatment cream.