I also have problems with short term memory and it used to worry the hell out of me however I've got used to it now. Medication can help but it can also make symptoms worse so it's important to take note of this and share your concerns with your Neurologist, PD Nurse or GP.
I notice my memory gets worse when I am due for medication. I can feel my thought processes slowing down and when someone talks to me they may get a delayed response. I often struggle for the right words to say when this happens.I also forget what I am doing from one minute to another especially if multi-tasking - I try to stick to one task at a time. I hate being rushed, I can't cope with the pace. I have to be organised or my mind feels like chaos. I also place my keys, mobile, medication, diary and glasses in a bowl in the middle of the table, that way I can find them.
Below is a useful link. Also you can search the forum for more topics about memory problems - just click on 'search forum' (side menu,top left of forum)http://www.parkinsons.org.uk/pdf/FS95_mildmemoryproblems.pdf