See your GP as soon as possible. If you're ill for 7 days (I think that includes non-working days) you need a certificate anyway. Most employers give time off for bereavement but only for immediate family, not aunts, uncles, grandparents etc. Don't take your boss's attitude to heart - if she's been ok before it probably means she's extremely stressed because one of her key staff (you) is off and also very worried because you've got an infection on top of your kidney disease.

My boss let me have the day my mum died off and I had to have holiday for the funeral (my previous employers would have sent me home for 2 weeks on full pay). Don't automatically ask your doctor for a month off, see what he thinks. I only get one month sick leave on full pay so unless you're on limitless fully paid sick leave try for a week and then go back if you're still not up to scratch.

Assuming you can't cancel or postpone the parties can you reduce the number of people you're entertaining? I'm sure they'd understand once they know the circumstances, or if not you must ask them to help out with catering and clearing up. The most important thing is to try to reduce your blood pressure - your reading is high (but home kits aren't always totally accurate and you must remember to sit still for a while before using them, not test too soon after food etc - the instructions are usually in the kit). I use a home kit to keep a check on my high blood pressure and know that if I test twice in an hour I can get vastly different readings.