Thanks, Twinks for your comment. I've seen my Dad today and he was a bit better. He's not taking any Parkinson's meds and he's only taken 1 of the anti depressants. Although I had the OK from the helpline nurse, I have told my Dad not to take anymore until we have spoken to his team. I would prefer to have the green light from them. We've already had one mistake, not sure I can cope with another.
The anti depressants take a few weeks to kick in, so one week of not taking them won't change the situation. Plus because there seems to be an improvement over night in his condition, he may not need the anti depressants altogether.
Also eileenpatrica has mentioned in her post that there are certain anti depressants that can only be taken with Parkinson's meds.
All a learning curve, I would rather be safe than sorry.
Thanks once again for the information.