A few weeks ago I was taking my kids to bed,I started choking I guess must have been on saliva.It was very scary.Kids were great hitting my back and telling me not to panic, breath in and out slowly.Luckily its just happened that once.Like you said its very scary.Have you seen gp or spoken to pd nurse about it yet?
I cant be much help but I know there are nurses at hand to chat to you and offer advice on pds helpline CALL FREE on 0808 800 0303
Also there are information sheets you can download from pds website. http://www.parkinsons.org.uk/pdf/FS22_040208_web.pdf
I hope you don't have a long wait to see your pd nurse.
Take care Dot x