@RebecccaE I realised that no one has replied to your question about Dizziness and Double Vision.
Firstly can I tell you that I a m no expert just that I have learned things over the 15 years nearly that I have been diagnosed with Parker's .

The dizziness could be that your blood pressure is lower now because of the medication that you take which lower's it.
When you feel dizzy, is it after you have suddenly stood up or bend over and then straightened up again.?

I may be a idea to ring and get an appointment with your Parkinson's nurse or General practise (Doctor or nurse) just to take your blood pressure both standing and sitting. From lying down to standing up.
In relation to your eyesight . It is a fact that some people can experience deterioration of their eyesight for the first few years of being diagnosed or prior to diagnosis of Parkinson's.
Go to your optician and have your eyes tested .. That may give a clue why you have double vision. The other explanation my be your medication for Parkinson's , check the contra indication's or ring your Parkinson's nurse or Neurologist.

Ring their secretary if you cannot get the question to the neurologist. I hope this helps you