Yes , it is difficult to unpick symptoms from existing diseases from new ones, that are LC related. Try to get a tilt table test then for PoTS…it should just effect your HR, BP not effected unless you have hyper PoTS ( not a term really used here in UK, but refers to specific eg where adrenaline dump involved so Bp and HR too). You can try a DIY PoTS test at home, look at NASA lean test, but although I thought I had PoTS from mine it did not pick up the dropping BP, needed the sophisticated proper tilt table test. Have a look at the US ‘Standing up to PoTS’ or ‘ POTS Uk’ websites for lots of info. that might help, like tips with keeping hydrated or wearing compression socks. I keep a diary of BP/ HR linked with what I have been doing: eg getting dressed, going up stairs to toilet…standing at the stove trying to cook a cheese sauce is my consistent worse task… always has been bent double on a chair as though I have done a 4 minute mile!