Potential cancer polycythemia Vera constantly ill

so i am a female 24 was fit and well till 19 i then got a lung infection ended bedbound for 2 weeks developed asthma had never had asthma started getting heart problems with heart rate and blood pressure no drs ever took me seriously when i said how poorly i felt until recent i was blue lighted to resus because my heart was beating so fast and caused actue pericarditis then found out they are testing for polyctheima vera i have alot of symptoms ive also got no energy englarged lymphnodes in my lungs and grion i feel so so ill and my health has got worse and it keeps getting worse i feel like im dying and if its not blood cancer what else could it be?? im exhausted from feeling so ill and just being called lazy the drs know something is wrong but they cant find out what my heart beats at like 140pm resting and my blood pressure is through the roof even with medication i feel so lonely and drained im exhausted i have to have a cardiac monitor for 7 days next week but im so tiered