My mother in law had 3 brain tumours removed around 13 years ago, including one in her pituitary gland. 
Unfortunately approximately 2 years ago another small tumour grew in the front of her brain just above her eye and while it has caused vision issues in the left eye, it hasn't changed significantly in that time.

For the last few months she hasn't felt 'herself'. She has always been a worrier but this has become far worse and she is convinced her old tumours have returned despite only having a brain scan just before Christmas. This isn't helped by the fact that she has what looks like a bony lump at her hairline, just by her scar and naturally she is wondering if this is another tumour. 

She is taking hydrocortisone to help raise her blood pressure to stop her going into a 'low' and needing emergency assistance, while at the same time taking blood pressure tablets to lower it!!

She's complaining of headaches and severe sweating and has been trying to control these symptoms by upping her blood pressure tablets, but whenever I take her BP it's on the low side. (She has a machine at home) 

I've told her of my concerns and that she really needs to see a doctor, but she feels that her doctor dismisses her concerns - and given that she has a 30-40 a day smoking habit I don't blame him - she really isn't helping herself. 

So my question is - how do I help her? I'm terrified of her self medicating. She's already o'd' on medication previously but won't stop buying additional medications to add to her cocktail of meds. She gets through a pack of paracetamol in a day or so and she really seems to think that she needs them. 

I just don't know what to do or say anymore to make it better.