Was it originally fastened at the front? Cabinets are usually attached to the back wall. Check and ensure that it has not become loose on the back wall and is actually tipping forward. If the back is loose retighten the screws which should pull it upwards. and if you feel it necessary catch a ceiling joist and put an L bracket there. Ensure that you catch a joist though so that it does not just pull the ceiling panel down.
1999 Winnebego Chieftain
Wayne & Leila and Teddi (the Kid in the brown fuzzy pyjamas)
Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us.