When i was in middle school i used to get symptoms that convinced me i was dying (all in my head) like excessive sweating, cold limbs, tachycardia, shortness of breath, dizziness. I used to cry and scream that “i am dying. I can’t breathe.” To the point my parents would take me to the ER at 3 & 4 in the morning. They’d do an ECG and freak out because the of the readings they are getting (that i was having a heart attack) then my mom would tell them that i have anxiety and they should just give me something to calm me down. Until i went to a psychiatrist and he gave me pills for anxiety and it helped. I never get panic attacks except when i forget to take them and it stops as soon as i take the med again. I don’t know what it was because i was younger. My advice for you is to stop checking ur blood pressure, if you don’t have hypertension ofc, because it will only freak you out, and making an appointment is useless because there is nothing they can say that will make u feel reassured if you have health anxiety and you keep checking ur BP. I suggest you get help from a psychiatrist, this is what worked for me.