There are several reasons for feeling like you can’t speak well: 1. You may be too nervous and anxious, and you will be especially worried and afraid when you speak, such as worrying about making a fool of yourself, sweating, or having a trembling voice, and you may not be able to speak well. 2. You may have a slow brain response or a decline in intelligence or attention span, and you may not know what to say, or you may not be able to speak well. 3, It may also be caused by some old age diseases and organic brain diseases, such as Alzheimer’s disease patients because of memory loss caused by incoherent speech, or patients with brain infarction, cerebral ischemia and other diseases may also have the sequelae of incoherent and unclear speech performance.