It is difficult to understand what is going on without a photo. When you say "left side has dropped", I assume you mean the eyelid margin is lower. If this is the case it is not uncommon and will probably resolve with time. I tell my patients to massage the lower eyelid in an upward and lateral direction to prevent scar contraction. Swelling and scar tissue remodeling can take months to completely resolve. Be patient and share your concerns with your surgeon and follow his or her instructions.
Please consider posting a photograph.
Things do happen after lower eyelid surgery. However without a photograph, it is impossible to know what is going on. It is very difficult to identify an individual from an eyestrip. I encourage you to repost with the photos so the Realself community can be of more service to you.
Are you able to forward some photos to allow an assessment of your problem? Make a follow-up appointment with your surgeon. He should be able to advise you.