Pip Change of Circumstance

Hello everyone,
I am currently receiving PIP, but awaiting a tribunarl hearing as I was awarded 2 points less than my dla lifetime award and lost my disability car January this year I had what though was just me passing out, never happened before but was taken by ambulance to A n E, after Ct scan and xrays I was informed I had what looked like calcium deposits in two places in my brain, Now been to see Neuro consultant, who on my first visit assured me after having follow up MRI scans that he didn't think the tumour yes tumour was cancerious and was what he thought historical. Still awaiting my Trib date, was told I maybe seen sometime in Sept 18 due to back log here in Burnley. In May 18 I had a second passing out, again ambulance called was taken to A N E checked over and told to contact Neuro Consultant, was given an immediate appointment, who was surprised to see me, thinking the first seizure was a one off, he now decided to say he couldn't leave me like this and said I had Epilepsy, this was a massive shock as Ive never had anything like this before the stress facture of the change over from DLA indefinite to PIP, losing 2 points and my independence the car. I now have to see a Neuro surgeon on Wednesday 18th July, really worried to be honest. I informed the PIP who said I would have to send in a change of circumstance form... I was wondering if there is anyone to advise me on what is the best way to complete this form as I cant seem to find any information guides. Please if you can help I would be ever so grateful, its bad enough being worried about the Wednesday appointment with the Neuro surgeon, just don't know where to turn. Sorry for the rambling and spelling x