Hello, I Am On Amitriptyline For Fibromyalgia Pain. I Am

Hello,
I am on amitriptyline for fibromyalgia pain. I am seeing a black blob at night while lying in bed. I thought it might be floaters resting in a different position because I am lying down. I am concerned. Could it be this medication that is new to me? I went to a retina specialist and everything seems to be okay. So why do I continues to see this black blob. It resembles the form of a moving tarantula in its web. Very strange.