If yes. Does it change its shape in every disease, or does it remain in the same shape and cause several diseases?
Yes, one type of bacteria can cause multiple diseases. For example:
"Rheumatic fever is caused by group A Streptococcus. This bacterium causes strep throat or, in a small percentage of people, scarlet fever. It’s an inflammatory disorder." [https://www.healthline.com/health/rheumatic-fever#causes].
The difference is in how the individual's immune system responds to the infection (and how the infection is treated). Everyone responds a bit differently to the same infection.