When did you last service it? The correct grade oil and genuine oil filter should be renewed every 10,000 miles or 12 months whichever comes first.
None genuine filters have been known to collapse and cause low pressure.
Check the dipstick - has the poor thing got any oil in it - the level needs to me up to the mark. Check your oil level at least weekly.
Run it as it is and you'll quickly wreck the engine.
ChicksFan
October 2014