Struggling with Mental Health and Physical Symptoms

I'm really struggling with mental health- severe depression, but I also feel in the past couple months like physically something is wrong and I haven't felt that way before despite years of mental health issues. The only other thing was migraines which I have mostly under control with meds now. But now I have been extremely fatigued, have been experiencing palpitations, tachycardia of like 120s-150s at times, nausea, and pain and tenderness in my upper left side. I went to the ER last month & had an abnormal EKG with inverted T waves in lower & lateral leads, and elevated inflammatory markers but nothing else really notable. I have a cardiologist appointment for late October which has been rescheduled by the facility and pushed back so it'll have been 2 months by the time I'm seen. I also feel like because I have a diagnosis of anxiety that nobody takes me seriously and chalks everything up to panic symptoms even though I'm not panicked at the time. Not sure if anyone has helpful words they can share but I'm feeling a bit discouraged and it's hard for me to speak up about my concerns feeling I will again be dismissed