Hello mate, first of all I hope your using a low pressured Reg ?
if you were using the gun shooting paint, the symptoms your saying is very often just a broken ball in the chamber ?
take out bolt put a fluffy through and re-grease bolt, usually puts things back to normal ?
at times the "O" ring at the base of the grip going to oops goes, usually if the gun has too much PSI going into it , or maybe Air Spiked high from bottle ?
as above with what CWKOTW says is Good to do,
also try another bottle.