Macbook Pro 13 Editing Problems

I have a Macbook Pro 13 with Retina display, purchased in 2015. I am having problems with simple editing. While typing, the cursor will erratically move from one location in the document to another. It occurs in all apps. Also, the editing function locks and I lose access to the cursor altogether. Nothing will bring it back - not the escape key, a control/alt/delete press, the enter key or the space bar. It will eventually snap out of it after continuous tapping on keys but I cannot ascertain what is causing it and what brings it back to proper functionality. Any ideas? Thanks in advance.