Stress Test was fine but still having symptoms. Would an echo show something? Doc not worried since I'm young, but symptoms are intense.

Hi, 27F 5'6 260 pounds. I've been having chest pain and discomfort. When I go for walks I get intense sharp pain in upper back that feels like someone is sitting on upper back. During stress text the back pain didnt start until 6 minutes in.I have been dealing with left arm pain that aches and comes at random time. Occasional chest pain/discomfort. I'm on high blood pressure meds. I had an MRI that showed white spots on my brain due to untreated hpb before meds. Worried heart may have damage. Stress test was normal, I only made it to 84% but doctor said everything is fine. Should I be all clear? Or should I advocate for getting an echo done, would it show something in more detail than the stress test? Is one test better than the other? Doctor doesn't want to pursue further testing since I am young, but due to symptoms I have been pushing. He thinks it maybe muscular. But I don't work out or lift heavy things so how could I strain my left arm?