Dr says i have scar tissue on pleura/lungs after having pleurisy earlier this year. is this why i still get chest pain which is worse on exertion?

Nearly a year?: The pain from pleurisy does not least this long unless this is a chronic issue such as sle. No matter what, you need to see a rheumatologist to get it under control.

Could be: Obviously that is too complex of a question to answer with certainty over the internet, but it is a reasonable potential cause, particularly if your dr has evaluated you for more serious causes of chest pain, in which case nsaids or other pain management should help reduce limitation to function/mobility. Talk to your dr about this.