Agree with @bopper that having a STEM degree doesn’t preclude you from playing music. The advice I would give has already been stated… diagnose the back (don’t know where you live or what your insurance will cover but my step-mom had something wrong doctors couldn’t diagnose so took a trip to the Mayo Clinic. Their diagnostic program was crazy… she spend a whole day answering questions and by the next day they ran a couple tests they had narrowed to and she walked out with diagnosis and treatment plan for home. So look into that.) Finish your degree in some fashion whether switching majors, going part time to work on piano, or any combination of what has been stated. I say this because a school my son visited for physics had a physics professor who also had a Grammy. She followed her love of music while teaching high level physics. It can be done.